Add a basic spec for the init subcommand.
Add basic init subcommand that just generates an empty Podfile
Add a more thorough spec for init command.
Add init to command unit spec.
Base init implementation for generating from an xcode project.
Add an integration test for basic Podfile construction.
Address line note comments on code style.
Touch up some things to conform to best practices.

* Added some documentation for a couple private methods as suggested.
* Modified to the spec to explicitly include generating target modules.
* Use config.podfile.
Fix integration tests to account for changes to init command.
Implement default pods inclusion for the init subcommand

* 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.
Only use help! when validating command-line arguments.
Fix up an incorrectly handled rebase change.
Move templates into a separate templates directory.
Rename the template files to follow "Podfile.type"
Update spec for template filename change.
[Integration] Move pod init spec to the integration submodule