Fixed issue with minimumRequiredDiskSpace which was String. Changed unit to MiB.

Signed-off-by: Daniel (dmilith) Dettlaff <dmilith@verknowsys.com>
Implemented afterStart and afterStop merge with Default value. Extended tests.

Signed-off-by: Daniel (dmilith) Dettlaff <dmilith@verknowsys.com>
Implemented Disk space check. Will just do logError for now (no notifications center yet).

Signed-off-by: Daniel (dmilith) Dettlaff <dmilith@verknowsys.com>