clean up some stuff, use enum-like things
Merge branch 'platform' of github.com:ankurcha/bosh into platform

* 'platform' of github.com:ankurcha/bosh: (34 commits)
  User Bosh::Exec#sh for executing shell commands instead of backticks
  Depend on securerandom for uuid generation - ruby 1.9.x provides UUID generation out of the box so why use uuidtools
  add source .rvmrc in build scripts for now
  add .rvmrc file back for now
  remove scripts that source .rvmrc since we got rid of that file
  update aws-sdk to ~> 1.8.5, change RDS interactions to suit
  remove .rvmrc
  keep a reference for Tempfile to avoid being GC'd
  fix CPI test and enable debug log for it
  [aws_cpi] revert task_checkpoint changes in resource_wait
  [aws_cpi] fix resource_wait_spec
  [aws_cpi] move task_checkpoint into Helpers
  [aws_cpi] fix task_checkpoint in delete_disk
  [aws_cpi] show number of retries in debug log
  [spec] fake task_checkpoint in aws_cpi for use in publish_ami
  [aws_cpi] use another way to do dynamic method calls
  [aws_cpi] we need to ignore AWS::EC2::Errors::InvalidSubnetID::NotFound while waiting for subnets to be available
  [aws_bootstrap] Bosh::CLouds::Config.logger need to faked too
  [aws_cpi] yet another aws sdk quirk that needs a workaround
  [aws_cpi] fixed failing test case
  ...