First round of tests implemented
Simple tag parsing

Simple tag parsing now works.  This is the under pinning of the 'it' and
'at' motion listed in #791
Span information is working
Got the basic tag pipeline hooked up

On the road to #791.  Lots of work to do though.  It's still not hooked
up to Visual Mode for some reason.  That requires a bit of work because
we have to make sure that repeated calls to 'at' expand the selection
Tag motion hooked up to Visual Mode
Inner tag is now hooked up as well
Count is now hooked up properly

Closing in on #791.  Still a couple features missing

- Visual mode selection doesn't expand on repeated uses of a tag block
motion
- XML parsing is not taking into account attributes
Tag parsing now supports attributes
Expand selection in visual mode

This rounds out the feature.

closes #791
Merge pull request #1412 from jaredpar/fixes-791

This adds 'it' and 'at' support to VsVim

closes #791
closes #1094