Add some database-related gems

Added the following gems:

  * composite_primary_keys
  * foreigner
  * awesome_nested_set
  * paperclip
  * image_sorcery
  * nokogiri
  * state_machine
  * globalize3
  * simple_form
  * country_select
  * kaminari
  * rabl
  * activemerchant

Two gems are initialized in creation time:

  * simple_form
  * kaminari