Update IWebBrowser to incorporate all of the needs of Chorus

* Add ScrollLastElementIntoView to IWebBrowser
* Make DocumentText property behave the same in GeckoWebBrowser
  as it does in the Windows.Forms Browser
* Modify TestApp to allow for easier Gecko Testing
Address code review comments on Update IWebBrowser commit
Made AudioIrrKlangSession IDisposable and fixed StopPlaying to stop playing the current sound also.
Document a promise to reintroduce the DocumentText get
Merge pull request #37 from jasonleenaylor/ImproveGeckoFxWebBrowserAdapter

Update IWebBrowser to incorporate all of the needs of Chorus
Fix bug with GetDeviceNumber when there are spaces in filePath

Change-Id: I5ded3c438fedec22be875986ece62751a1639762
Support looking for AOR index.txt

The current ArtOfReading3FreeSetup.exe installs the index.txt file in
the parent directory of images.  The previous version of the code
looked for the index.txt file in the images directory.
Merge pull request #38 from sillsdev/RestoreAORSearchInImagesDir

Support looking for AOR index.txt
Fix spelling of "Enforceable"