[WIP] Several small init script additions/improvements

The lack of configuration parameters like custom user home, or custom user and a weird startup/shutdown behavior on CentOS brought me to this PR.

**What did I change:**
- Added default file for init script to allow configuration for the runner
- Updated install area inside ReadMe.md
- Adapted the indention of the switch-case to match the rest of the script
- Edited the stop()-method to stop killing runners if there aren't any
- Renamed uppercase variables to lowercase vars
- Updated the check-if-Im-root-method to use the "new" EUID way

**Important:**
Please double check stop() method (line 93) inside the init.d script. I moved some parts of it inside a else branch. The method now should not try to kill runners if it didn't find any.

**Testing:** 
I would be happy if more people could test/review it and let me know if anythign weird occured.
- [x] Ubuntu 14.04 LTS 64bit
- [ ] CentOS 6.5 64bit