first stab at simple linear color mapper in python
hook up colormapper to image glyph
handle all non-spec params correctly
update examples
update tests
Support JSON serialization for palette; improved error remproting
Modifed image downsample for python-side linearcolormapper
Catching up to 0.6.0 (ish) master
Fixing imports
image_rgb and contours don't fail with color_mapper.  image does fail, none really use it.
WIP: colormapper+server
Easier debugging.
Merged glyphspec removal.
merge master
Merge pull request #1116 from ContinuumIO/feature/colormapper

Color Mappers on python side