fix: last day of the month isn't cut

When you used --last-month, the 'till' timestamp was set to last day in month but time was set to 00:00. This caused the last day of the month was excluded. Now the time is set to last milisecond of the day, that means '23:59.999...'. 

spent 1h

fix: sort of worklogs

We cannot rely on how git iterate over commits. We need to do additional sorting when we have worlogs parsed. 

closes #4
spent 30m

feat: version information

Now you can see currently used version via:

    gitwrk --version

see #2
spent 20m

chore: fixed license name for snapcraft

spent: 5m

docs: increased version to 1.0.7

Spent 2m

chore: add DEB and RPM support for release

Spent 15m

docs: changed help text

Spent 1m