Don't use local config in unit tests.

+ Define a constant in phpunit.xml.
+ Only set __CA_LOCAL_CONFIG_DIRECTORY__ when not in a unit test.
Merge pull request #104 from leftclickben/PROV-916

PROV-916: Don't use local configuration in unit tests
PROV-913: (Follow-up bugfix) Add missing returns.

Hook methods weren't returning anything, which was preventing other plugins
from executing.  Returning the passed-in parameters (or true) fixes this.
Merge pull request #105 from leftclickben/PROV-913-bugfix

PROV-913: (Follow-up bugfix) Add missing returns.
PROV-915 Properly support RDF mode for XML exports with namespaces.

Previously we’d always try to run each record through DOMDocument again
for “pretty printing” (indentation and such). That could cause problems
in RDF mode because you usually wouldn’t define all your used
namespaces in all your mappings for the whole graph. DOMDocument
complains about undefined namespaces though. So we simply skip that
step in RDF mode, which means our formatting might be a little off, but
at least the XML is correct and complete.
Merge branch 'master-fix' into develop