Document the dependency on libuuid from e2fsprogs

At some point in the future, we might want to just pull in the uuid code into
the tree, but for now it's easier to go this route than untangle the autoconf
mess that exists in e2fsprogs

Fixes #2
Parcelling out mach and other Apple tie-nis within libvproc
libdispatch is used by launchd, and is available as a FreeBSD port, let's use it for now
More stubbing out of mach-specific code

Not everything is known to me at this point, in terms of what code must be
ported versus what should just be commented out for non-Apple OSes. In theory
that will be much more clear after liblaunch is building
Mention the IRC channel on the readme
Add liblaunch/test to start fleshing some fleshing some cmocka tests out
Disable ktrace unless on an Apple OS