CocoaPods and build.sh updates

- Updated podspec to support both iOS & OSX
- `clean` now removes all non git-versioned files (except `core/`)
- added `browser` target
- added `deploy` target
- added `pod-deploy` target
Good point! Though I don't think every project's derived data is set to the local build directory. Regardless, we should update all projects in the repo to use the local DD folder.