Support metadata when uploading objects

Add contentType and contentEncoding options to sendStream(). These
options will set the corresponding metadata on the object.

This changes the API. The fourth argument to sendStream() used to be the
source md5. Now, it's an options object and the source md5 is a property
of that object.

libraries/object-persistor/test/unit/S3PersistorTests.js

@@ -448,14 +448,11 @@ describe('S3PersistorTests', function () {
       })
     })
 
-    describe('when a hash is supploed', function () {
+    describe('when a hash is supplied', function () {
       beforeEach(async function () {
-        return S3Persistor.sendStream(
-          bucket,
-          key,
-          ReadStream,
-          'aaaaaaaabbbbbbbbaaaaaaaabbbbbbbb'
-        )
+        return S3Persistor.sendStream(bucket, key, ReadStream, {
+          sourceMd5: 'aaaaaaaabbbbbbbbaaaaaaaabbbbbbbb'
+        })
       })
 
       it('sends the hash in base64', function () {
@@ -468,6 +465,28 @@ describe('S3PersistorTests', function () {
       })
     })
 
+    describe('when metadata is supplied', function () {
+      const contentType = 'text/csv'
+      const contentEncoding = 'gzip'
+
+      beforeEach(async function () {
+        return S3Persistor.sendStream(bucket, key, ReadStream, {
+          contentType,
+          contentEncoding
+        })
+      })
+
+      it('sends the metadata to S3', function () {
+        expect(S3Client.upload).to.have.been.calledWith({
+          Bucket: bucket,
+          Key: key,
+          Body: sinon.match.instanceOf(Transform),
+          ContentType: contentType,
+          ContentEncoding: contentEncoding
+        })
+      })
+    })
+
     describe('when the upload fails', function () {
       let error
       beforeEach(async function () {