Merge pull request #33 from timaschew/master

put dependencies to package.json fixes #11
Add support for render tests.
Add a whole bunch of tests:

- Accidental Strategies
- Mixed tuplets
- Fret-hand fingering
- String numbers
- Override fret note
- Bass Tab
- 8-string tab
- Rests in Tab
- Tab Stems
- Tab Stem Direction