More fixes for Firefox XML namespace handling incompatibilities in package document parser
by using getElementsByTagNameNS() instead of jQuery selectors that
behave differently on WebKit than on other engines.
Convert all jQuery queries (that get confused by XML namespaces on Firefox) to getElementsByTagNameNS().
Merge pull request #50 from JCCR/more_firefox_xml_parsing_fixes

More fixes for Firefox XML namespace handling incompatibilities in package document parser