rake aborted! LoadError: cannot load such file

I am completely newbie to this rails frame work and learning via online tutorials. I am in the process of developing a simple application with the help of rails(rails+Mysql).

Currently i am facing an issue with "rake" command.

When i tried to "rake db:schema:dump" the following errors are coming.Pls suggest me some thing.

Thanks in advance.

harsha@Trebuchet:~/simp_cms$ rake db:schema:dump --trace
rake aborted!
LoadError: cannot load such file -- bundler/setup
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/harsha/simp_cms/config/boot.rb:3:in `<top (required)>'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/harsha/simp_cms/config/application.rb:1:in `<top (required)>'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/harsha/simp_cms/Rakefile:4:in `<top (required)>'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/rake_module.rb:28:in `load'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/rake_module.rb:28:in `load_rakefile'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/application.rb:689:in `raw_load_rakefile'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/application.rb:94:in `block in load_rakefile'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/application.rb:176:in `standard_exception_handling'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/application.rb:93:in `load_rakefile'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/application.rb:77:in `block in run'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/application.rb:176:in `standard_exception_handling'
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rake/application.rb:75:in `run'
/home/harsha/.rbenv/versions/2.2.2/bin/rake:33:in `<main>'

harsha@Trebuchet:~/simp_cms$ bundle exec rake db:schema:dump --trace
/var/lib/gems/1.9.1/gems/bundler-1.10.5/lib/bundler/shared_helpers.rb:78: warning: Insecure world writable dir /usr in PATH, mode 040777
Could not find debugger-1.6.8 in any of the sources
Run `bundle install` to install missing gems.

harsha@Trebuchet:~/simp_cms$ gem install debugger -v 1.6.8
Building native extensions.  This could take a while...
/home/harsha/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/ext/builder.rb:73: warning: Insecure world writable dir /usr in PATH, mode 040777
ERROR:  Error installing debugger:
    ERROR: Failed to build gem native extension.

    /home/harsha/.rbenv/versions/2.2.2/bin/ruby -r ./siteconf20150628-11403-1nydzd5.rb extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

My Ruby version, rails version and gem list

harsha@Trebuchet:~$ rails -v
Rails 4.2.2
harsha@Trebuchet:~$ rails -v
Rails 4.2.2
harsha@Trebuchet:~$ gem list

*** LOCAL GEMS ***

actionmailer (4.2.2)
actionpack (4.2.2)
actionview (4.2.2)
activejob (4.2.2)
activemodel (4.2.2)
activerecord (4.2.2)
activesupport (4.2.2)
arel (6.0.0)
bigdecimal (1.2.7, 1.2.6)
binding_of_caller (0.7.2)
builder (3.2.2)
columnize (0.9.0)
debug_inspector (0.0.2)
debugger-linecache (1.2.0)
debugger-ruby_core_source (1.3.8)
erubis (2.7.0)
globalid (0.3.5)
i18n (0.7.0)
io-console (0.4.3)
json (1.8.3, 1.8.1)
loofah (2.0.2)
mail (2.6.3)
mime-types (2.6.1)
mini_portile (0.6.2)
minitest (5.7.0, 5.4.3)
mysql2 (0.3.18)
nokogiri (1.6.6.2)
power_assert (0.2.3, 0.2.2)
psych (2.0.13, 2.0.8)
rack (1.6.4)
rack-test (0.6.3)
rails-deprecated_sanitizer (1.0.3)
rails-dom-testing (1.0.6)
rails-html-sanitizer (1.0.2)
rake (10.4.2)
rdoc (4.2.0)
spring (1.3.6)
test-unit (3.1.2, 3.0.8)
thread_safe (0.3.5)
tzinfo (1.2.2) 

Please find my database.yml file

  default: &default
  adapter: mysql2
  encoding: utf8
  pool: 5
  username: simp_cms
  password: secretpassword
  socket: /tmp/mysql.sock

development:
  <<: *default
  database: simp_cms_development

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: simp_cms_test 

please feel free to contact me for any more details...