Update status correctly when user submits evaluation

EV-127

The code was relying on the appraisal step to set the correct status
when a user submitted the evaluation. Instead the code now checks
appraisal.getNewStatus() to set the status properly.
Use the right appraisalStep to send mail

EV-127

Even though the correct status is used to update the evaluation record,
the email code was using the email_type from the appraisal_steps table.
The code now checks if the status used to update the evaluations is
different than the one in the appraisal steps, if it is, it uses the
correct email_type.
Add comments to a couple of methods

EV-127
Merge pull request #3 from osu-mist/feature/EV-127-set-status

Feature/ev 127 set status