* move the doc for it to the top of the script to be consistent with
other syntax checkers
* dont define a s:checker var - just use the
g:syntastic_perl_efm_program variable. This simplifies things slightly
previously we assumed the user had efm_perl.pl installed as part of the
standard vim runtime, but this isnt so for CentOS and possibly for other
distros - see issue #159. Therefore, we now ship it with syntastic
itself.
Note: efm_perl.pl just munges the output of perl into a different
format. It may be worth investigating further and writing our own
errorformat to remove the dependency on efm_perl.
