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
double square brackets are not POSIX compliant. They are used elsewhere in the script and I was thinking to remove them. Since we suggest to run the script with `sh` we should be careful about this.