Fix startup script

- Startup script should respect custom zk setting for marathon. Zk path should not be hardcoded and depending on local mesos setting (in case if Mesos Master and marathon runs on the same host)
- Only provides default if marathon custom configuration is not given. This is also be backwards compatible.
- line 63: remove additional space (invalid syntax)
Merge pull request #379 from QubitProducts/master

Fix bugs in startup script