Closes #1045

* Added default_podfile_path and default_test_podfile_path to Pod::Config
* Add behavior to Command::Init to read out the above paths into generate Podfiles when appropriate.
* Implemented tests for the relevant pieces of behavior.

* Added some documentation for a couple private methods as suggested.
* Modified to the spec to explicitly include generating target modules.
* Use config.podfile.

Actually change link to 1242

The number was updated, but the link is still wrong.

Reference the integration spec files from a submodule pointing to CocoaPods/cocoapods-integration-specs

[Specification::DSL] Add prepare_command

* master:
  [Gemfile] Require cocoapods-core from the master branch
  [Gemspec] Bump dependencies version