Reduced space between annotation cards.

Reduced space between annotation cards by 1/2. This is solves [issue 493](https://github.com/hypothesis/h/issues/493) and looks much nicer.
Merge pull request #518 from RawKStar77/develop

Reduced space between annotation cards.
Added some generated objects to .gitignore
Merge branch 'develop' of https://github.com/hypothesis/h into 514-simple-tagging-3
Fix VS input border CSS problem