Setting "Sync Protocol Listen Addresses" and "Global Discovery
Server" in the Settings dialog does not work. This bug seems to
have been introduced in 26d52be.
This sends the Cache-Control header to allow caching of static resources,
and checks the If-Modified-Since header to allow browser to use the
cached resource on refresh. Also fixes some paths that caused redirects
(core//foo -> core/foo)
The very deep tree structure didn't really aggree with me, sorry. This
makes the core module rather large, but on the other hand that just
highlights that it is rather large.
