VE-1588: Tests for ve.dm.WikiaTemplateModel

Because we make an API request to get all available parameters for a given template, we need to ensure that we don't add all of the empty parameters in the serialize() and getWikiText() methods. This test tests for this scenario.

https://wikia-inc.atlassian.net/browse/VE-1588
We're using QUnit v1.11.0 which doesn't have assert.expect. I'm going to leave it as QUnit.expect for now. We can change all instances of QUnit.expect to assert.expect when we upgrade.