ALLJOYN-1925 Add BusAttachment.Join to binding

Added the call to BusAttachment.Join to the SessionTest since this
seemed to be the best place to make sure Join was called. Tests
were running before cleanup of a conflicting test had completed
running this would  cause ER_DBUS_REQUEST_NAME_REPLY_EXISTS errors.

Also added BusAttachment.ReleaseName to the SessionTests to make sure
the names were cleaned up between tests.

Some additional white space cleanup.

Change-Id: I92370350c7b3660fadc55dce9897a671ae296868
Added several more method calls to the Unity Extension

The following methods were added
   - BusAttachment constructor that lets user specify the number of concurrent callbacks
   - BusAttachment.EnableConcurrentCallbacks
   - ProxyBusObject.IntrospectRemoteObject

Unit test ConcurrentCallbackTest was added.  We may not need the EnableConcurrentCallbacks
method in the current AllJoyn Unity Extension design because of the Deffered Callback used
in the Unity Extension.

Change-Id: I1d53aa9973a8e461ee86bb17a33d17cc422fb128
Updated the gitignore file

Added files to the gitignore file that are generated by Microsoft
Visual Studio when developing and debugging code.

Added files to the gitignore file that are generated by Unity

Updated the SCons script to copy xunit.dll into the build path used
by the MSVS solution this make build running and debugging unit test
simpler.

Change-Id: I6467c7896adbd5850b7448017f6d90ad728009d1
ALLJOYN-1926 Unity Samples should not be part of the Windows SDK

Change-Id: I75c4db990dc1c89b9bf10ed2453928c887a45461