fix syntax for new doc metadata
Always prefer explicit note arg over opts value in note fn.

Fixes #74
Use the absolute of the rate when calculating sample_duration.

Fixes #72
Further docstring work.
start working towards web interface compliance again...
add another docstring
Add a test!

To support tests:

* Move sonic pi rb files into a lib/sonicpi
* Create Test dir
* add Rake file (to run tests do rake test)

The Test:

* Tests a simple aspect of note resolution
* Required extra cases for note keywords to pass
Add some more note tests and fix up functionality accordingly.
start playing around with Travis for CI
Add Travis status image
Add further tests and a minor fix w.r.t. note
properly short circuit note resolution with return
Add further note tests - also unify pitch class
Format note tests and throw in few more asserts
Increase precision of note matcher regexp and
customise exception.
Raise InvalidNoteError over generic RuntimeError
Add further invalid note tests
Report and test for invalid octaves to note
Fix synths and FX:

* Zawa wasn’t being properly panned (only came out of left speaker)
* IXI Techno FX didn’t honour slide controls and freq was in Hz rather than MIDI notes.
Fix mod_dsaw to use envelope params correctly