Refactoring iPython Notebook support

DRYer, more semantic
Merge pull request #17 from singingwolfboy/ipython-notebook

Refactoring iPython Notebook support
Now write_midi excepts a list of instruments to use for each track written to the MIDI file, and each track gets its own MIDI channel.
Merge pull request #18 from smcq/master

Run unit tests under nose
Merge branch 'master' of https://github.com/jtauber/sebastian

Conflicts:
	sebastian/midi/write_midi.py
Merge pull request #19 from pmargani/master

write_midi now maps each track to its own channel, and instruments can be specified.
add .ipynb exclusion to gitignore
Added another 'unit' test to test_write_midi.py
Merge pull request #20 from pmargani/master

Added new 'unit' test to test_write_midi.py
Merge branch 'master' of github.com:jtauber/sebastian
note in readme about running tests
Added two different ways to construct the shortning bread song under projects
Merge pull request #21 from pmargani/master

Added two examples of shortening bread
Added a SeqBase.zip() function to unify the elements of two sequences.
Fixed an errant class doc.
supress warning during octave check
Merge pull request #22 from DeadWisdom/master

Added a SeqBase.zip() and Tests