System.Data and System.Transactions for Windows Phone 8

This is just a first pass at modifying the source code files to be able to be build for Windows Phone 8. There is still a little more to do for Windows Store apps.

Most of the functionality is the same except for several things:
 - Binary Serialization (not available on WP)
 - The SqlClient namespace (will be made available in future)
file will leak if writer creation or WriteStartDocument throw exception. Move the initialization in the try/finally block