Using Fixtures docs in API RDoc needs work

The current "Using Fixtures" documentation notes three methods of accessing fixture data from within Rails tests:

1. By using a hash stored in an instance variable named after the fixture e.g. @blobs['foo']['name']
2. By using an instance variable named after the record name, e.g. @foo.name
3. By using a dynamically-created object, e.g. blobs(:foo).name

However, the default has been to not instantiate instance variables, which means only method #3 AssetTagHelper should accept a slightly wider range of protocols will work. Furthermore, all examples don't use the test method for each test case.

Recommend moving method #3 AssetTagHelper should accept a slightly wider range of protocols to be the primary method, and note how to enable methods #1 Migrations will not run on a fresh database and #2 rake rails:freeze:edge on windows. Update examples to show this, using the new test methods.

Complete writeup here: http://smerpology.org/sprocket/a...