Added sql to insert signatureDueNotRated for emailing

EV-185

In addition, changes to the Mailer, AppraisalsAction,
Appraisal classes and Email properties were made. The
AppraisalsAction class now checks if it is appropriate
to send an email to the upper supervisor.
Added some extra logic to account for possible null values

EV-185
Added description and tests for isRated()

EV-185
Merge pull request #60 from osu-mist/feature/EV-185-email-upper-supervisor-not-rated

Feature/ev 185 email upper supervisor not rated
Changed the logic behind the isOverdue() function

EV-519

Previously, the isOverdue() function would check to
see if the isDue() returned <= 0. Only a return value of
<= 0 is attributed to the status of "overdue". However, the
function could have been checking if isDue() == 0 because of
the time of day that the cron job that updates appraisals
and such occur. It would make sense if it occurred later
in the day, rather than the start of the day.
In addition, I noticed that the signatureDue message for
signatureDue-today was not quite right, so I changed that
as well.
Added tests for the isOverdue() and isDue() functions

EV-519
Fix unit tests based on code review

EV-519

* remove invalid unit test for not rated IT evaluations
* minor fixes to overdue unit tests
Merge branch 'feature/EV-519-status-incorrectly-overdue' into liferay6