Release v0.5.3

Production release of dsnap-sync (fork of snap-sync)

Functional highlights:

1. support posix shell (e.g. dash)
2. create snapper conform metadata and filestructures
3. support snapper template for dsnap-sync
4. dry-run functionality
5. verbosity output
6. ssh integration for remote snapshots
7. progress indication in interactive mode (via pv)

for a complete list, please hava a look into the git log output.