Adds SPM support for 2.x.x

Merge branch 'swift'

- Moved files in preparation for parallel release of obj-c and swift pods

- Updated access modifiers for methods and properties

- Added jazzy documentation generation script

- Documentation fixes

- Added documentation for TimeChunk, TimePeriod, and TimePeriodCollection classes

- Docs for comparators and components fixed

- Fixed documentation for Date+Comparators

- Finished Examples

- Started TimePeriods example

- All inits set to public

- Removed landscape from example app.

- Extensions example complete

- Made initializers for TimeChunk public