Better error message on import error

I was missing flask, not redis. Also, the pip installer doesn't auto-install flask for some reason.
just print the error message and exit
Merge pull request #222 from omellet/master

bokeh-server ImportError handler just prints the error message
fixed #223
fix typo in map frmo screen
less top distance on the gridplot toolbar so it isn't obscured at all
dev setup for bokehjs,
 - supporting incremental builds
 - coffeescript source maps
 - separate js files, vs a single combined bokehjs file
TODO:
 - extend this to bokehjs demo/test files
 - think about removing all the static files from bokeh/server/static
- fixed template to use bokehjs_file endpoint for serving bokeh.js
- fixed typo, naming boostrap2 vs bootstrap
Merge pull request #227 from ContinuumIO/feature/js_dev_setup

dev setup for bokehjs,
fixed #214
don't have two identical glyphs in example
expose nonselected glyphsepc in plotting.coffee
add rbush to project for use in hit testing
First step to Python 3 support.

Some of the examples haven't been converted yet, also there is a metaclass
issue in MetaHasProps.
Fixed six.moves import.
Removed wrong error message.
Fixed sampledata download.
Fixed CSV reading in sampledata.
Fixed examples.
Fixed metaclass.