updates for before_id
simple test for before_id
Added map type for server APIs.
Fixed date mapping issue for message
Merge pull request #39 from cameronwebbable/feature/pagination_update

Changed Pagination to use "before_id" instead of "page" for messages
Fixed timezone.
Merge pull request #40 from jcgsxr/fix/timezone

Fixed timezone.
Changed readonly to copy and strong for message properties.
Merge pull request #41 from jcgsxr/fix/property_type

Changed readonly to copy and strong for message properties.
Add stream object and API.
Added stream import.
Fix CI cocoapod version issue.
Merge pull request #42 from jcgsxr/feature/stream_object

Feature/stream object