Port manpages to MarkDown and use autotools

(also known as the "Don't tell my girlfriend I did this on Christmas"-pull request)

Shout out to @rubenk for helping with autotools.

 * Add disable-dnssec to pdnssec docs (closes #641)
 * Make manpages consistent with eachother
 * Expanded missing options
 * Removed old manpages
 * Added --with-docs and --with-manpages configure switches

Comment more than welcome :smile: