Fixes #3811 updating to bootstrap 3

fixes #2741 - remove dash from -%> to %>

Feature #2368 - i18n extracting strings

fixes #2277 - adds spice html5 support

This also adds a newer version of the web socket proxy (where we
probably need to use an external package instead of vendor it).

we still allow users to use the old XPI based spice client (which would
ensure end to end security as well) via a 'new window' button....