(QENG-845) Beaker junit xml: XML Parsing error

- need to strip out invalid characters from strings before printing to
  xml, these characters are still invalid even if wrapped in a cdata
  tag
Merge pull request #371 from anodelman/xml

(QENG-845) Beaker junit xml: XML Parsing error
(QENG-922) Add `puppet_user` and `puppet_group` DSL methods.

Signed-off-by: Wayne <wayne@puppetlabs.com>
(QENG-992) `puppet.conf` must be usable by puppet user.

Signed-off-by: Wayne <wayne@puppetlabs.com>