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

[jccr]

This fixes more instances of jQuery selectors being used to parse a package document's XML DOM.

This caused a certain book I was testing with (in FF 30) to load with an empty spine.

[jccr]

@aadamowski I believe you are familiar with this issue, can you review this pull request for me?

[danielweck]

The code diff looks fine to me, but could you please fix the metadata parsing as well? (so that this PR addresses all occurrences in the document parser)
Are you aware of other occurrences in other JS files?

[jccr]

The only other two instances I see are:
publication_fetcher.js

    this.getRootFile = function(containerXmlDom) {
        var rootFile = $('rootfile', containerXmlDom);
        var packageFullPath = rootFile.attr('full-path');
        return packageFullPath;
    };

var rootFile = $('rootfile', containerXmlDom);

smil_document_parser.js

    // Parse a media overlay manifest item XML
    this.parse = function(spineItem, manifestItemSMIL, smilJson, deferred, callback, errorCallback) {
        var that = this;
        publicationFetcher.getRelativeXmlFileDom(manifestItemSMIL.href, function(xmlDom) {

            var smil = $("smil", xmlDom)[0];

var smil = $("smil", xmlDom)[0];

[jccr]

@danielweck I have updated the PR to handle metadata parsing and other miscellaneous uses such as cover href parsing.

[aadamowski]

Hello @jccr, the changes look fine to me.