Lockerproject.org doesn't mention other deps

[merc3po]

Lockerproject.org download section mentions Git and Python are needed, but not the curl, build-essential and libssl-dev packages (Which by default are not installed in Debian Squeeze and probably a few other distros.)

(Moved this on behalf of elsmorian from here LockerProject/Locker#626)

[elsmorian]

Ta for splitting and filing these :)