Remove output minifier

This feature has proven to be problematic and it's not nearly
as flexible as a dedicated minifier library like Minify
(http://www.minifier.org/, https://github.com/matthiasmullie/minify).

The same results in terms of saving traffic can also be achievied via
gzip compression (which should also be done on the httpd level, but we
also support anyway) and stuff like mod_pagespeed.

Reverts PR #965

Related issues as a track record proving how problematic this has been:

#2078 #1499 #2163 #2092 #2387 #2637 #2710 #2120 #2171 #2631 #2326 #2795
#2791 #2772

Additionally, the count of contributors suggesting that the only way
to fix the minifier problems is to remove it, is around the same as
the count of people suggesting the feature to be implemented in the
first place. It was experimental anyway ... the experiment failed.