Consistently use Square's mockwebserver

Google mockwebserver merged into OkHttp as per:

https://code.google.com/p/mockwebserver/
JCLOUDS-619: Introduce MultipartNamingStrategy to generate part names correctly.
refactor BaseComputeServiceLiveTest to simplify the extension of this base test
JCLOUDS-607: ComputeService.createNodesInGroup throws NPE on FloatingIPApi.create()
Avoid extra copy with Splitter result
Use consistent stage for the two-stage injection
Upgrade to logback 1.1.2

Changelog:
http://logback.qos.ch/news.html
JCLOUDS-410: Remove InputStreamSupplierPayload

ByteSourcePayload replaces this.  jclouds 1.7 deprecated
InputStreamSupplierPayload and Guava 16 deprecated InputSupplier
itself.
JCLOUDS-417: Remove ConsumeOnCloseInputStream

ConsumeOnCloseInputStream can potentially perform a copy in finalize()
if the stream was not closed properly.
JCLOUDS-417: Test closing a stream w/o reading it
Enforce correct MD5 for local blobstores

Matches behavior of real blobstores.
Remove unneeded InputSupplier helper

Also convert byte[] to HashCode.
JCLOUDS-622: Deprecate Strings2.toString

Guava 16 deprecated InputSupplier.
Improve use of ByteSource with test resources

This commit ensures proper resource cleanup, simplifies
initialization, and paves the way for purely synthetic inputs in a
subsequent commit.
Address Checkstyle violations
JCLOUDS-622: remove calls to InputSupplier methods

Guava 16 deprecated these methods and Guava 18 will remove them.
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