start introducing less
start to migrate to variables
start mixins
Revert "remove less.css"

This reverts commit 076a0fac5a12d4b674f2343f484a2c983a410219.
use less for tooltip
remove useless classes
main_app -> ipython-main-app
add less flag
generate style.css
less flag in templates
fix print css less
make file and other less
readd flexible-box-model
Add and remove boostra squashed commit

To reduce branch size as bootstrap is huge

add default bootstrap theme
does not import code in bootstrap
remove bootstrap
recompile css
fix cell type selector css
Fix project path url in dashbord

Use Bootstrap breadcrumbs for later navigation purpouse
slight typography changes
clean css.

remove some Ui-widget where unnecessary,

Don't show toolbar on media-print
regenerate minified css