Squashed 'subtree/bokehjs/' changes from 074d4ef..fa902cc

fa902cc Removing calls to no_scroll and restore_scroll in EventGenerators, because the addition of the hidden class was causing layout issues for the Zoom and Save tools

git-subtree-dir: subtree/bokehjs
git-subtree-split: fa902ccbeca20870c19b590507471f4da19819f0
Merge commit '6545dc07ef8f4b232038a6b89a4ce316b368f5a8'
Merge branch 'master' of github.com:ContinuumIO/Bokeh