Ignore hphp/hack/Makefile
Add links to hhvm and hack websites
Fix Hack link error
List for links
look for hand-compiled image magick
Stop mentioning the built in webserver
Fix typo in README
add explicit int64_t cast

OS X has trouble deciding between an int and int64_t in this case.
add long unsigned int conversion to Variants

Primarily solves compilation for Imagick, but should prevent a lot more
complaining on OS X in the future since we prevent confusion on what to
do with unsigned types that might not be 64bit.