First working embedded asset version

Extended templates/templates to enable monkeypatching of the template
sources map.

Implemented the templates with embedded assets, replacements for
js.html.go and header.html.go in the default distribution.

Updated bindata.go with a 1.8.2 version of jquery just for safety's
sake. Also, moved the twitter-bootstrap subdirs under a 2.2.1 subdir to
better match the default nsqadmin templates.

Implemented a use-embedded-assets option for nsqadmin

Implemented setting the html Content-Type heaader correctly for css and
js content
Initial commit of necessary templates with embedded assets