Squashed 'subtree/bokehjs/' changes from 323b60f..9404d1a

9404d1a  now both tests and demos tempaltes link back to root
c4e95a8  added test list to the welcome page
210df28  basic landing page
b0a4adf Updating README
2d8abba remove cruft
e81a594 tighten up auto_interval return, and add a few tests
e0775bc a few ticking tests
7c40fc7 more test tweaks
fac6f5a fix allpossibletests target
2308498 fix some tests
bc024a7 add try_active_tool trigger for passively triggered tools to try and become active
25ca2aa some filename/naming consistency
f8d89af minor improvements to resize too
0dc88fc much improved resize tool and some css tweaks
ed74f71 some tool refactoring to make it easier for tools to draw
eab8b1d some changes to accomodate tool views
9a879f9 some cleanup for PlotView, reorg as render_init, render_canvas, and render
8567747 first cut of a resize tool
0b077e4 fix typo

git-subtree-dir: subtree/bokehjs
git-subtree-split: 9404d1adfd972d97a84d416bddccbc3762fa5fb2
merged in latest bokehjs master
 trying to figure out why the PreviewSaveTool isn't showing up and the zoom tool still is
 bokehjs now seems to work properly after the merge
merged master in
 a hacky way of getting pngs to render instead of canvas
 now there is a PNGListView that uses PNGViews instead of PlotViews
 now PNGListView creates Pngs if they don't first exist
 PNG plot titles are only shown when they exist, PNGs thumbnails sizes are parameterized with thumb_x and thumb_y