Pisync

This software has been tested by me personally on my own machines by doing backups of my precious files. I intend to keep the API the same, but if I am to find any bugs or things that need fixed I cannot guarantee that breaking changes will not occur. Therefore, I am creating this release in case there is someone who doesn't want me commiting directly into the main branch.

- Write rsync stderr stream to log file with severity "ERROR"
- Avoid potential deadlocks due to any of the other OS pipe buffers filling up and blocking the child process.
- If backup fails log messages with severity "CRITICAL"

- Write the stdout of rsync to the log file in real time instead of capturing all stdout and writing at the end of the process.