The blob read operation should print to STDOUT.

The Blob read operation accepts a --display option, which causes it
to print the contents of the blob. However, the contents are printed
to STDERR, as opposed to STDOUT.
JCLOUDS-76: Add blobstore-blob-exists command

This is less confusing than overloading blobstore-read.
JCLOUDS-31. License header cleanup
fixing jclouds-71