Removes addl XML parse step on report generation.

Code was needlessly parsing XML and HTML reports through REXML and
Nokogiri. It will be faster and less memory intensive to just pass the
string along, since #to_s was called on the resulting parse. If
we need to validate the XML for reports, that should be done in testing.
Bumps to latest version of rex.
Merge pull request #98 from sgreen-r7/master

Refactor/Extract Common Credential Module
Removes Nokogiri dependency #97 ... not used.
Convert to_map to to_hash, #94.
Switching to 0.9 for next release version.
Allow ad hoc reports to bypass XML parsing.

Attempts to address #99
The generate method can now be passed with a "raw" flag to indicate that
the response should not be parsed as XML for exception handing.
Example usage:
```
  config = AdhocReportConfig.new('audit-report', 'raw-xml-v2', site.id)
  report = config.generate(nsc, 3600, true)
```