Move repos_dir to .cocoapods/repos
Move config.yml path back to cocoapods dir.
Fix some text references to .cocoapods to be .cocoapods/repos
rename cocoapods_dir to home_dir
Migrate existing repos when running setup.
Fix up some comments and add a missing test for config.
Move tempo repos generated by spec_helper to a repos subdir.
Add a test for migrating repos to new repo dir.
Clean up config/sources manager interfaces to not be polluted with old directory structure stuff.
Add a note to the CHANGELOG about directory restructure.
Remove an incorrect unit test.
Merge pull request #1233 from ianyh/cocoapods-directory

Restructure .cocoapods directory to contain repos as a subdirectory.