[FIX] Properly ignoring files for helm-projectile-ack

Currently helm-projectile-ack processes ignored files and directories
the same as projectile-ack. This works for directories, but not work for
ignoring files with wildcard matching. When user adds files with
wildcard, ack will see this not as an argument to it but a search
string and returns no result.

This change properly fixes it by using "--ignore-file=match:" pattern
that accepts a regex that matches files. Also, shell-quote-argument must
be used to properly pass the file patterns with regex in it, otherwise
ack also returns no result.