Add option to wrap model.createRecord in runloop

[jbryson3]

Summary

This PR adds the ability for users to opt into wrapping a model.createRecord in an Ember run loop. This is to avoid this error: "You have turned on testing mode, which disabled the run-loop's autorun." encountered in older versions of Ember.

Changes

• Added a Codeshift options section to the documentation to explain how to use the new option, what it does, and why you might need to use it
• Added the ability to pass in jscodeshift options for a test. This is done via an input test naming convention - the-test-name.option1=foo.option2=bar.input.js
• Cleaned up the code a bit in the createModel section so its easier to read. This was accomplished by putting the nested 'j' calls in a named functions, and then calling those functions later.

p.replace(createRecordExpression(createRecordArg));

// instead of
p.replace(
  j.callExpression(
    j.memberExpression( //....
 ));

Dependencies

Depends on and branched off of #116

[Turbo87]

what do you think about having something like a setup-model-test2.options.json file instead of encoding the options in the filenames?