Add 'six' to requirements lists
Py3: experimenters.aggregator
Py3: experimenters.barchart
Py3: experimenters.frequency
Py3: experimenters.lilypond and indexers.lilypond
Py3: experimenters.template and indexers.template
Py3: indexer
Py3: indexers.interval
Py3: indexers.ngram
Py3: indexers.noterest
Py3: indexers.offset
Py3: indexers.repeat
Py3: models.aggregated_pieces
Py3: models.indexed_piece
Py3: WorkflowManager
Py3: tell Travis-CI to test against py3.3 and py3.4 too
Merge branch 'master' into devel_py3

Conflicts:
	setup.py
Update VERSION_HISTORY and version for a 2.1 testing release with Py3
Add ISMIR2014 paper to README
New: Importing no longer uses/stores cached pickle files.

Previously, every import would store its Score as a pickle, or try to load the
pickled Score from a previous load. This isn't likely what we want for VIS,
since we will implement our own cross-user caching, and the time it takes to
store as a pickle is wasted anyway.