functional tests for simple blobstore client

  head request needed explicit headers for Basic auth
integration test for package_cache
remove commented out code
more test for simple blobstore server
silence cpi output
[finishes #45642021] - director uses new style blobstore properties
Add retry around EBS disk attachment
Don't worry if the blobstore has stuff in it
Adding new exception in resource wait for instances
[release] director job spec should use 'provider' instead of 'plugin'
another missed blobstore property
force detachment of the EBS volume when deleting volume after stemcell creation
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  force detachment of the EBS volume when deleting volume after stemcell creation
  another missed blobstore property
  [release] director job spec should use 'provider' instead of 'plugin'
  Adding new exception in resource wait for instances
  Don't worry if the blobstore has stuff in it
  Add retry around EBS disk attachment
  [finishes #45642021] - director uses new style blobstore properties
  silence cpi output
  more test for simple blobstore server
  remove commented out code
  integration test for package_cache
  functional tests for simple blobstore client