Tests: Copy missing resources.groovy among plugins

Copy missing resources.groovy from base plugin into api, administation
and reporting plugins.  Else, tests (grails test-app) fail for these
plugins with ClassNotFoundException: resources
Tests: Metadata: fix output from similarExcludingID

In metadata tests, fix the output from similarExcludingID.  If this
method call from a "then" clause of a Spock test returns false, the
output from the test (the error reported) includes only the call to this
method - result, method name, arguments.

Calling this method with a simple Diff object means only the the first
difference (which typically is the ID attribute ignored by this method)
is printed and the actual XML difference found is hidden away.

Change the code to instead convert the simple Diff to a DetailedDiff
before calling similarExcludingID - that way, all differences captured
in the DetailedDiff are printed and the test errors are much easier to
track down.
Tests: metadata: fix validUntil timezone to UTC

Some tests in the metadata plugin were using hard-coded timestamps but
these timestamps were interpreted relative to the current timezone - and
in other timezones then Australia/Brisbane caused the tests to fail as
the value would not match the UTC-pinned value in expected output.

Explicitly set the timezone to UTC in the tests and adjust test data
accordingly.
Merge pull request #156 from University-of-Auckland/aaf-develop

Fix several issues with tests: