JCLOUDS-251: Swift: Delete chunks when deleting a multipart blob

https://issues.apache.org/jira/browse/JCLOUDS-251

I'm trying to implement support for deleting chunks when deleting a multipart blob and I'd appreciate some help if anyone has time to help out...

1) The approach I've taken is to just automatically delete the chunks with no option to leave them, is this OK?

2) There are no tests for my new code. I found the existing tests for the code I've changed quite hard to understand, can anyone help out (either by writing some tests or helping me to understand them)? One thing to note is that I'm not familiar with Guice and there seems to be quite a bit of Guice magic going on in this project!

Note that I do have some test code in another project: https://github.com/brightinteractive/jclouds-prototype/blob/1cfa515b15658b3b7f74b2714dbf5b47fb4e14f2/src/test/java/com/brightinteractive/jclouds/PutGetDeleteMultiPartTest.java. This test passes when run against the 'bright' branch of jclouds, which has this JCLOUDS-251 branch and some other fixes merged into it.

3) General code review.