Return nothing if we find invalid date like Feb 30th
Clean up waste space
JIRA: Move projects into YAML for easier maintenance.

In addition to fixing #378, this should also make it easier if it
turns out that there are more JIRA trackers to be supported later.

The major overhead is the crazy-long generated regex trigger for
recognizing the tickets.
Rename submodule, making more sense
Refactor regular expession
Merge pull request #514 from heytitle/bug-workdays-invalid-input

#394 Bug workdays invalid input
Merge pull request #518 from mwmiller/jira

JIRA: Move projects into YAML for easier maintenance.