JCLOUDS-427: Upgrading Guava 16.0 -> 16.0.1

Fixes Guava issue 1635.
JCLOUDS-432: Revert "JCLOUDS-427: Avoiding Guava reflection code broken in Java 7u51"

This reverts commit 8ff60020f85ae5d9f57e9a25a6342fb7b00e1d2a.
Improve use of Splitter in Atmos code
JCLOUDS-137: Retry on HTTP 500 AtmosError 1040
Moving dependencies for the Checkstyle plugin into a profile

Follow-on from 335f594
Removing unused Sonatype OSS plugin snapshot repository
JCLOUDS-470. Include region in group name for AWSEC2SecurityGroupExtension.
JCLOUDS-467. Properly iterate over node names for EC2 instance creation.
JCLOUDS-473: Close FileInputStream in Wire.copy

FileBackedOutputStream.asByteSource.getInput returns a FileInputStream
which we do not close.  We later call FileBackedOutputStream.reset
which removes the underlying File.  This fails on Windows which does
not support deleting an open file and leaks resources on other
platforms.  Eagerly close to address this issue.
Address Checkstyle violations
Prefer ByteSource over deprecated InputSupplier
JCLOUDS-459: Limit maximum user threads

Previously jclouds could use an unlimited number of threads on its
user ExecutorService.  While this ExecutorService will go away when we
complete deasyncafication, we should prevent jclouds from misbehaving
until that time.
Add ByteSource Payload support for Clojure
JCLOUDS-410: Remove StreamingPayload

Only two tests use this class.  Callers should use ByteSourcePayload
or InputStreamPayload instead.
Address error-prone warning
Remove WriteTo

Guava helpers capture this functionality in a more idiomatic way.