Support new platforms and modernization

[briancroom]

I've been putting this branch together over the past couple weeks. It includes:

• Support for watchOS and tvOS dynamic frameworks, as well as installation on these platforms via Cocoapods
• Spec targets for validating Cedar on these platforms (although not as part of any rake tasks yet)
• Reorder and rename targets (& associated schemes) for consistency
• Clean up directory structure for the specs and bundles
• Use a shared Info.plist for the spec bundles
• Miscellaneous housekeeping in the project file

[tjarratt]

This was sorely needed. Thank you so much Brian for finding the time and energy to reorganize and cleanup the project structure.

This seems good from a cocoapods and carthage perspective, and I just updated some of my personal projects (that consume Cedar as a git submodule for iOS and OS X) without any problems, so this seems good to merge.