Update to LibGit2Sharp version 0.14.1.0
Add support to Visual Studio 2013 (close #16)
Deletion was shown one line to high
Fix margin doesn't appear for .html files (close #9)

TextDocumentFactoryService.TryGetTextDocument(TextBuffer, out _textDocument) returns null _textDocument for html, cshtml and javascript files.
Replace the usage to find the filename by _dte.ActiveDocument.ActiveWindow.Document.FullName.
Update ReadMe to add support of Visual Studio 2013
Update version to 1.2.0