JCLOUDS-402: Allow Guava MediaType Content-Type

This promotes type-safety.  Keep the String interface for unknown
content types.

blobstore/src/main/clojure/org/jclouds/blobstore2.clj

@@ -303,13 +303,15 @@ Options can also be specified for extension modules
            blob-builder (if content-length ;; Special case, arg is prim.
                           (.contentLength blob-builder content-length)
                           blob-builder)
+           blob-builder (if content-type
+                          (.contentType blob-builder content-type)
+                          blob-builder)
            blob-builder (if calculate-md5 ;; Only do calculateMD5 OR contentMD5.
                           (.calculateMD5 blob-builder)
                           (if content-md5
                             (.contentMD5 blob-builder content-md5)
                             blob-builder))]
        (doto blob-builder
-         (.contentType content-type)
          (.contentDisposition content-disposition)
          (.contentEncoding content-encoding)
          (.contentLanguage content-language)

blobstore/src/main/java/org/jclouds/blobstore/domain/BlobBuilder.java

@@ -26,6 +26,7 @@ import org.jclouds.blobstore.domain.internal.BlobBuilderImpl;
 import org.jclouds.io.Payload;
 
 import com.google.common.io.ByteSource;
+import com.google.common.net.MediaType;
 import com.google.inject.ImplementedBy;
 
 /**
@@ -119,6 +120,8 @@ public interface BlobBuilder {
 
       PayloadBlobBuilder contentMD5(byte[] md5);
 
+      PayloadBlobBuilder contentType(MediaType contentType);
+
       PayloadBlobBuilder contentType(String contentType);
 
       PayloadBlobBuilder contentDisposition(String contentDisposition);

blobstore/src/main/java/org/jclouds/blobstore/domain/internal/BlobBuilderImpl.java

@@ -36,6 +36,7 @@ import org.jclouds.io.payloads.PhantomPayload;
 
 import com.google.common.collect.Maps;
 import com.google.common.io.ByteSource;
+import com.google.common.net.MediaType;
 
 /**
  * @author Adrian Cole
@@ -205,6 +206,11 @@ public class BlobBuilderImpl implements BlobBuilder {
          return this;
       }
 
+      @Override
+      public PayloadBlobBuilder contentType(MediaType contentType) {
+         return contentType(checkNotNull(contentType, "contentType").toString());
+      }
+
       @Override
       public PayloadBlobBuilder contentType(String contentType) {
          payload.getContentMetadata().setContentType(contentType);

blobstore/src/test/clojure/org/jclouds/blobstore2_test.clj

@@ -123,7 +123,7 @@
     (is (= "http://localhost/container/path" (str (.getEndpoint request))))
     (is (= "PUT" (.getMethod request)))
     (is (= "10" (first (.get (.getHeaders request) "Content-Length"))))
-    (is (nil?
+    (is (= "application/unknown"
          (first (.get (.getHeaders request) "Content-Type"))))))
 
 (deftest sign-put-with-headers-test