Replaced direct init.d script calls with service calls

For more (confusing and conflicting) info, see: http://askubuntu.com/questions/2075/whats-the-difference-between-service-and-etc-init-d
Moved pre/post tasks into prepare & cleanup roles

Resolves #23
Merge pull request #22 from evolution/initd-service-issues

Replaced direct init.d script calls with service calls