Refactor to make it easier to extend and override CMSBootstrap bundles.

For example you can incorporate them into your own bundles, and override
the default blocks to load your bundles instead, reducing the number of
separate JS/CSS requests needed to load both your own scripts and
CMS Bootstrap.

Remove the hacky script loader by default. Just use script tags, OK?
If you dn't believe me, read this:
http://www.html5rocks.com/en/tutorials/speed/script-loading/

Move the IE version checking script out of line into a separate file.