Fix isoDateTime and isoUtcDateTime masks, improve test.

v1.0.9 has a broken isoDateTime and isoUtcDateTime masks due to global single/double quotes replacement https://github.com/felixge/node-dateformat/commit/efa4fe3eae8a4047ac632ab2a46fa4733b09f0d1

In v1.0.9, dateformat generates invalid ISO dates like these: 2014-11-26"P"13:19:44 and 2014-11-26"A"11:19:44"UTC"
While in v1.0.8, those dates are generated correctly as 2014-11-26T13:19:44 and 2014-11-26T11:19:44Z
ISO date reference: http://en.wikipedia.org/wiki/ISO_8601

Other than the above issue, the test also broke due to missing 'should' require when test was executed using mocha.
The test expectations seem to be geared to pass only if the test machine is on GMT+2 . Just a note that some expectation strings that include GMT and UTC will break when tested elsewhere (e.g. I'm on GMT+11). I'll leave it to the original author of the test to change it if the intention is to work in any TZ.