spec: rails3 models/pseudonym_spec

Pseudonym#infer_defaults initializes account in a
before_validation callback.

Change-Id: If17ed2cc51bc285d1efae588d8130d5329b8f203
Reviewed-on: https://gerrit.instructure.com/29702
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
Product-Review: Jon Willesen <jonw@instructure.com>
QA-Review: Jon Willesen <jonw@instructure.com>