Emulate multipart upload with single-part uploads

This approach requires three times as many operations as the optimal
approach.  Implementing this correctly requires exposing the
underlying multipart operations in jclouds.  Most s3-tests pass but
two still fail:

test_multipart_upload_size_too_small
test_list_multipart_upload

References #2.

README.md

@@ -10,7 +10,7 @@ Features
 --------
 * create, remove, and list buckets (including user-specified regions)
 * put, get, delete, and list objects
-* copy objects and delete multiple objects (emulated operations)
+* copy objects, delete multiple objects, and multi-part uploads (emulated operations)
 * store and retrieve object metadata, including user metadata
 * authorization via AWS signature v2 (including pre-signed URLs) or anonymous access
 * listen on HTTP or HTTPS
@@ -95,7 +95,6 @@ Limitations
 S3Proxy does not support:
 
 * single-part uploads larger than 2 GB ([jclouds issue](https://issues.apache.org/jira/browse/JCLOUDS-264))
-* multi-part uploads
 * POST uploads
 * bucket ACLs ([jclouds issue](https://issues.apache.org/jira/browse/JCLOUDS-660))
 * object ACLS ([jclouds issue](https://issues.apache.org/jira/browse/JCLOUDS-732))

src/main/java/org/gaul/s3proxy/S3ErrorCode.java

@@ -51,6 +51,7 @@ enum S3ErrorCode {
             "Length Required"),
     NO_SUCH_BUCKET(HttpServletResponse.SC_NOT_FOUND, "Not Found"),
     NO_SUCH_KEY(HttpServletResponse.SC_NOT_FOUND, "Not Found"),
+    NO_SUCH_UPLOAD(HttpServletResponse.SC_NOT_FOUND, "Not Found"),
     REQUEST_TIME_TOO_SKEWED(HttpServletResponse.SC_FORBIDDEN, "Forbidden"),
     REQUEST_TIMEOUT(HttpServletResponse.SC_BAD_REQUEST, "Bad Request"),
     SIGNATURE_DOES_NOT_MATCH(HttpServletResponse.SC_FORBIDDEN, "Forbidden");