fix bug with error reporting on perl <= 5.12.x

apparently the call to new() for a Mouse object involves an eval in earlier Perl versions
this exposed a bug which I'm rather surprised wasn't discovered before
which is that the regex we build to determine what to skip demands something _inside_ one of the packages we specify
	we check both the method and the package against this
	when the package is exactly equal to the package we're checking against, that check fails
	happily, the method is still inside that package, so _that_ check succeeds
	except in this case the method was `(eval)`, so that failed too
	the solution was to allow exact package matches to succeed as well
also made the regex a bit nicer via /x while I was in there
also removed useless specification of Method::Signatures::Parser,
		since that's automatically caught by checking for Method::Signatures