JCLOUDS-629: SshjSshClient Payload without length

sshj treats -1 as an unknown length and uses a less efficient copying
mechanism.
JCLOUDS-40: Unasync OpenStack Nova API
JCLOUDS-625: Set VolumeBuilder id to nullable in VolumeImpl

VolumeBuilder does not allow null id while VolumeImpl allows it to be nullable.
Improve use of ByteSource
Reduce Swift integration test input size

Previously testMultipartChunkedFilenames uploaded 55 MB and now it
uploads 5 MB.
[JCLOUDS-474] refactor SoftLayer support
JCLOUDS-40: Unasync Rackspace Cloud Identity
JCLOUDS-622: Remove most vestiges of InputSupplier

Guava 16 deprecated InputSupplier and a future release will remove it.
JCLOUDS-622: Remove last vestiges of InputSupplier

Guava 16 deprecated InputSupplier and a future release will remove it.