Nudge v0.2.0

This version brings Nudge to almost beta level. The tool can be used to send notifications every day, yet its configuration file and command line interface is not stable yet.

New in this Version
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- Configuration file can be overloaded via command line.
- Logging level can be configured via config file and command line.
- Startup procedure is improved. Defaults are overriden by configuration file, which are overriden by command line arguments.

Known Issues
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- Logs can't be redirected to files via configuration file or command line, yet. These options are not handled in the code.
- Configuration sanity checking doesn't check everything for acceptable values.
- Not all features provided by Pushover is implemented (image attachments, HTML formatting, and possibly others)