Fix Issue #33 and #20

Issues Fixed:

Issue #33 - The Projects property on the DTE object only includes top level projects. Added a new method that loads projects inside solution folders when checking if a file should be saved.

Issue #20 - TFS items were being saved (and submitted) while being edited and this was partially fixed by PR #28 however there were still being saved when there were unsaved changes if you switched to a different document. SaveAllTheTime will now ignore TFS items which prevents them from being submitted prematurely.

Issue #23 - Appears to have been fixed in a previous version and/or an update to snippet designer. I tested this PR with the latest version of snippet designer and there were no issues, so this issue can be closed.

Also, there were some issues with VisualStateManager.GoToElementState being called from the wrong thread. I tried to fix this with an ObserveOn(RxApp.MainThreadScheduler) but this did not work. Included the call to Dispatcher.BeginInvoke to fix this.