first & lastDate 'enabled' range - (Thanks @Hout)

This first commit is the result of the merge of @Hout work.
PR submitted #6 & #12 where not mergeable as is.
Fix: Wrong lastDateMonth calculation.
Use UITabBarController in Demo Application
Expose Controller in Delegate Methods

Delegate Methods generate the warning on purpose, unfortunately the warning will not pop in the user implementation of the delegate.
Retrieve number of days per week from calendar
Add: Base for Unit Testing & Basic Tests
Update podspec to 0.6 & README
Merge pull request #14 from jivesoftware/develop

First/Last Date Range, Unit tests base, Improved Demo App