Make type of test's assert argument more helpful

[jzaefferer]

Depends on jquery/grunt-jquery-content#54

Based on #55.

[leobalter]

Short story: we should be able to do this:

diff --git a/entries/QUnit.test.xml b/entries/QUnit.test.xml
index fd08c08..eaa1402 100644
--- a/entries/QUnit.test.xml
+++ b/entries/QUnit.test.xml
@@ -9,7 +9,7 @@
                <argument name="test">
                        <desc>Function to close over assertions</desc>
                        <type name="Function">
-                               <argument name="assert" type="Object"></argument>
+                               <argument name="assert" type="Assert"></argument>
                        </type>
                </argument>
        </signature>

And set a reference link to the custom type.