Update Development documentation
Update Development documentation

Include references to the extra dependencies as well as instructions on getting
M2Crypto.

chaiku/fedmsg,fedora-infra/fedmsg,chaiku/fedmsg,pombredanne/fedmsg,vivekanand1101/fedmsg,cicku/fedmsg,vivekanand1101/fedmsg,maxamillion/fedmsg,pombredanne/fedmsg,chaiku/fedmsg,fedora-infra/fedmsg,fedora-infra/fedmsg,pombredanne/fedmsg,vivekanand1101/fedmsg,cicku/fedmsg,maxamillion/fedmsg,maxamillion/fedmsg,cicku/fedmsg