Fix Plivo install process and configuration
Code review mark-ups
Merge pull request #49 from Metaswitch/fix_plivo

[Reviewer: Andy] Fix Plivo install process and configuration
Optimized infrastructure recipe
Tidy up some ugly bits
Improve support for multiple regions - select correct image correctly, and handle deletion/cleanup
Merge pull request #51 from Metaswitch/faster-chef-client

Reviewer Mike - Faster chef client
Merge pull request #52 from Metaswitch/multi_region

[Reviewer: Andy] Improve support for multiple regions