trunk-tracking: update from r3696 to r3714

https://code.google.com/p/modpagespeed/source/detail?r=3697
 * system test improvements

https://code.google.com/p/modpagespeed/source/detail?r=3699
 * moved some config from location block to server block
 * system test improvements

https://code.google.com/p/modpagespeed/source/detail?r=3707
 * tests for OptimizeForBandwidth
   * had to switch tests from directory blocks to server+location blocks

https://code.google.com/p/modpagespeed/source/detail?r=3708
 * update to a test that had never been ported

* ngx_pagespeed.cc:
  * change in signature of FindIgnoreCase

https://code.google.com/p/modpagespeed/source/detail?r=3689
 * Was apparently skipped with #591.