remove comments when evaluating PKGBUILD

When a single line extracted from the PKGBUILD contains a hash sign,
every following line will be regarded as a comment by eval and thus be
discarded. Removing all comments bevor evaluating fixes the issue.
condense sed into grep

Using a perl regex, both commands can be merged into one.
Merge pull request #9 from dffischer/master

support comments in PKGBUILDs