Add support for Azure Copy Blob

Presently lacks support for CopyBlobOptions.  API reference:

http://msdn.microsoft.com/en-us/library/dd894037.aspx
Unfortunately `RestAnnotationProcessor.buildHeaders` does not replace headers with headerParams.  The following:

```java
   @Named("CopyBlob")
   @PUT
   @Path("{toContainer}/{toName}")
   @Headers(keys = AzureStorageHeaders.COPY_SOURCE, values = "/{fromContainer}/{fromName}")
   ListenableFuture<Void> copyBlob(
         @HeaderParam("fromContainer") @ParamValidators(ContainerNameValidator.class) String fromContainer, @HeaderParam("fromName") String fromName,
         @PathParam("toContainer") @ParamValidators(ContainerNameValidator.class) String toContainer, @PathParam("toName") String toName,
         Optional<CopyBlobOptions> options);
```

results in:

```
fromContainer: fromcontainer
fromName: fromblob
x-ms-copy-source: /{fromContainer}/{fromName}
x-ms-version: 2012-02-12
```