Merge pull request #98 from Bowman74/master

Added Android build constant.
Added generic IRestClient interface + JSON client

The client implementation is located in Plugins for the reason that
HttpClient on WP8 requires Microsoft.Http async library and I did not
want to introduce that dependency to all clients. I will try to put in
a ProtoBuf client at some point.

This client implementation depends on the serializer interfaces in the
core project.
Fixing the missed rest client core files
Updating with hashtag for the projext Closes #68

https://twitter.com/search?q=xflabs
Yet another fix to RestClient

Copied the implementation, forgot to include the interface
ProtoBuf REST client added + code comments
Better exception handling when ViewModel resolution fails
Merge pull request #100 from hellomonovo/master

Better exception handling when ViewModel resolution fails
Code cleanup
Merge pull request #16 from XForms/master

Merge from Main