Release 0.2

- Standardized Shebang lines and option descriptions
- Changed program version to 0.2
- Implemented safer authentication mechanism for
``satprep_schedule_downtime.py`` (Issue #17)
- Implemented unschedule function for
``satprep_schedule_downtime.py``(Issue #18)
- Moved schedule downtime code into ``satprep_shared`` to make it
easier to integrate with other scripts
- Fixed bug with detecting patches/errata requiring reboot in
``satprep_schedule_downtime.py``
- Renamed some options and removed authentication using options in
``satprep_schedule_downtime.py``