Skip testDirectory on S3

This test cannot succeed due to the way directories are implemented as
prefix pseudo-files in S3.
Allocate new container name using prefix

Before we used the previous container name, which kept appending and
hit S3 limits during integration tests like:

Caused by: java.lang.IllegalArgumentException: Object 'gaul-blobstore27-4348532805015069992-1155797412711190448-1465016400636204031' doesn't match S3 bucket virtual host naming convention. Reason: Can't be null or empty. Length must be 3 to 63 symbols.. For more info, please refer to http://docs.amazonwebservices.com/AmazonS3/latest/index.html?BucketRestrictions.html
Simplify testPutFileParallel

Create only one temporary file and use explicit delete instead
finalization to remove it.
Support Integer.MAX_VALUE size PUTs

Previously jclouds enforced Integer.MAX_VALUE - 1 size.  Tested
against Atmos Online.
JCLOUDS-166, JCLOUDS-167 - Removing async from vcloud and Terremark APIs/providers
Cleanup of Client->Api getters for vcloud
Add trailing slash to Atmos listDirectories

This is more consistent with examples in the Atmos programmer's guide
and allows this operation to succeed when used with ViPR.
Reduce testPutFileParallel input size to ~160 KB

Previously this test uploaded ~10 MB in 30 seconds which failed on
slower connections, causing spurious test failures.  The larger input
size provides no benefit.
Run some filesystem integration tests

Previously no integration tests ran, now we see:

Tests run: 43, Failures: 0, Errors: 0, Skipped: 8
Enable some Xlint warnings

Also address a handful of warnings.
Reduce testFileGetParallel input size to ~160 KB

Previously this test downloaded 45 MB in 30 seconds which failed on
slower connections, causing spurious test failures.  The larger input
size provides no benefit.
Upgrade to Guava 15.0-rc1

Release notes:

https://code.google.com/p/guava-libraries/wiki/Release15
[trivial] Simplify use of Optional.or

Also correct checkArgument call.
Explain expected result in filesystem test