spec: rspec2 --tags for parallel_excluded specs

Change-Id: I20bf507acb2d0c26d34220d8e52fdf02cbde3e12
Reviewed-on: https://gerrit.instructure.com/32627
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Shawn Meredith <shawn@instructure.com>
Product-Review: Shawn Meredith <shawn@instructure.com>
QA-Review: Shawn Meredith <shawn@instructure.com>