When creating new schedule, gracefully handle intervals like "8-12"

[smithfarm]

Currently if you enter an interval like "8-12" an awful error message is generated:

DBI reports DBD::Pg::st execute failed: ERROR: invalid input syntax for type timestamp with time zone: "2015-03-23 8" at /usr/lib/perl5/site_perl/5.18.2/App/Dochazka/REST/Model/Schedintvls.pm line 157.

One option would be for the JS to transparently add :00 before sending it on to the server.

An even better option would be to do the transformations server-side, in handler_schedule_new - for example, if it received an interval "[2015-05-25 8, 2015-05-25 12)", it would convert it to "[2015-05-25 8:00, 2015-05-25 12:00)". It could also take intervals like "MON 8-12".