Fix dependencies
First version of multi-perl testing tool

Mostly untested (and the test command is untested altogether) and
totally undocumented.

Basically if it can find its cfg file (warning: Will look in
author_tools where my default file is), it'll install the perls listed
there and dependencies into them, then go ahead and install the modules
from our repos also, by doing:

  perl author_tools/jitperls.pl install

Very high verbosity:

  perl author_tools/jitperls.pl -v=2 install

Custom config:

  perl author_tools/jitperls.pl --config=... install

Only one of the perls:

  perl author_tools/jitperls.pl install --perl=v5.18.1-thread

Also has the following commands:

  install (our stuff)
  install_deps (other stuff)
  build_perl (the perls)
  do (run one-liner using given perl)
  test (run tests of our components - currently untested)