Merge pull request #34 from bmcfee/develop

Merging in preparation for 0.2
pointing nbviewer to the new demo
Update README.md
added boolean support for cmap
absvaled ref_power in logamplitude
versioning up to 0.2.1-dev
default hpss power -> 2
octwidth -> 2 by default
cqt resolution -> 2 by default
fixed some logic in display color mapping
speedup in cqt aggregation
constant_q filters can now pad to constant length
adding util module, axis_sort()
added utilities to docs
adding file walker
lint score++
axis_sort optionally returns the sorting index
added axis_norm()
refactored chromagram to use axis_norm
renamed axis_norm -> normalize, refactor chroma