Added conditional statement for mod_headers.c, how to check system config.

Adding the conditional mod_headers.c is safer than dropping in the straight statement.
Added config check step
Added (better) Apache reload and graceful restarts.

Very tired, I hope I didn't mess this up:p
Merge pull request #59 from indolering/patch-1

Added conditional statement for mod_headers.c, how to check system confi...