Added cache-control header to objectstore

[rodrigolourenco]

Added the header Cache-Control on objectstore.

[coveralls]

Coverage increased (+0.01%) to 80.557% when pulling d1c7d25 on rodrigolourenco:cache-control-objectStore into ff42b6a on rackspace:master.

[coveralls]

Coverage increased (+0.01%) to 80.557% when pulling c8f234b on rodrigolourenco:cache-control-objectStore into ff42b6a on rackspace:master.

[rodrigolourenco]

@jrperritt I think this is ready for review, would you mind taking a look?

[jrperritt]

+2