Switch from jquery UI to Bootstrap.

Major update to SmokeStack to switch things over to use Bootstrap
instead of Jquery UI. The only things left using Jquery UI are:

-dialogs (still need to switch them over to use bootstrap modal)
-accordians (just a couple of these... need to use tabs instead or
something else)
Add bootstrap.js to assets.precompile.
Add package_builder branch configuration.

Drops deb_packager_url and rpm_packager_url in favor of
just packager_url.

Adds a new packager_branch configuration option which is
now exposed in the UI.

Consolidates the builder shell code in a common 'build_packages'
shell function.