Revert "templates: Remove jQuery -- not currently using it"

Um. Oops. Bootstrap depends on it...

This reverts commit c6d40f7fd473ac140436b16fb2a303d28e02fa7e.

Conflicts:
	templates/general.html
templates: splash->pagebanner

Rename the splash element to pagebanner, and make it more configurable
across different pages. This is a first step to implementing the grey
banner as shown in #43.