Updating the API doc for 'throws'

Removing the String comparison option.
Adding the Error instance comparison option.
Adding the callback comparison option.

Related to jquery/qunit#547.
Related to jquery/qunit#579.
Related to jquery/qunit#593.
1.14.6
Entries: Fix assert's type

Fixes #55
1.14.7
Entries: Add reference to assertion methods for test() and asyncTest()

Fixes #55
Closes #57
1.14.8
Entries: Notify of QUnit.push deprecation
Entries: Document assert.push