turn planet into a module

there has been an older attempt to do this
that had to be reverted due to a bug causing
puppet issues

so this is along the lines of
https://gerrit.wikimedia.org/r/#/c/54502/3
https://gerrit.wikimedia.org/r/#/c/58495/ etc,

but entirely new and _doesn't_ do things like dropping
the role class, putting config into module etc.

Change-Id: I980f9dc9f48e80d53dd2c920622ae67672d575df