Add test case query and test case selector along with a reload button

Add ability to retrieve test case queries and then execute those queries
to get the actual test case list.
Added a "reload" button that throws away any changes and reloads the
steps from the originally retrieved test case data.
Updates based on feedback from ajryan
Deleted commented out value and removed DiscardChangesCheck function

Commented out _testCaseNumber to find where it was used and forgot to
delete it after fixing where it was used.
Forgot to delete DiscardChangesCheck after migrating the internal code
back to CloseCurrentTab
Added null check for TFS project, fixed connection status on failed connection.

Added a null check to the Select Query functionality that pops a message
saying to ensure connectivity and to select an available test project.
Noticed that the _testStateToolStripLabel.Text value said
"Connecting..." even though the connection failed. Set it to replicate
the _changeProjectToolStripButton.Text value of "(not connected)".
Merge pull request #2 from mikepoz59/master

Add test case query and test case selector along with a reload button