Convert current location gem and search pin annotations to tangram marker interface

[msmollin]

After discussion with @tallytalwar we should convert the current location gem, the driving icon, and the search pin annotations to use Marker objects.

[tallytalwar]

Search pins can use Marker interface, maybe any polygon or polyline example could use MapData (clientdatasource) interface.

[msmollin]

Bah yeah I got it backwards in the ticket description. Edited and fixed.