Added service file permission variables

[c-erb]

• variable for owner, group, mode
• explanation in readme
• removed unnecessary and broken become_user statement

[c-erb]

As it is a quick change, I performed it. See #58

[ikke-t]

Sorry for late notice, thanks for a good change!

[hmoffatt]

Is this not pushed to Galaxy? I pulled the role from there and I don't seem to have this improvement. Thanks.