Modify Strings2.urlDecode to input a string.

This is consistent with urlEncode.  Also consistently use urlDecoder in
DecodingMultimap for values.
Handle quoted ETags for OpenStack objects to fix JCLOUDS-247

This avoids a 'java.io.IOException: Unrecognized character: "' when a quoted ETag is encountered (which happens when getting a multipart blob from Rackspace Cloud).
JCLOUDS-251: Swift: Delete chunks when deleting a multipart blob

Also:
- Make SwiftBlobIntegrationLiveTest.testMultipartChunkedFileStream more realistic by uploading a file large enough to be split into parts.
- JavaDoc fixes for SwiftBlobStore: don't reference nonexistent methods.