controls.sh: Properly exit the outer "control.sh" run

control.sh re-executes itself with the "script" tool to keep a transcripts of
its run. The outer "control.sh" however is not exited properly after "script"
finshes. Causing it to run the main code a second time under certain
circumstances (e.g. when booting in the "debug" state)
Merge pull request #131 from rhafer/fix/pebbles/control_sh

https://github.com/crowbar/barclamp-provisioner/pull/131

Merged by devtool for cloudsleuth