Show a pretty progressbar when uploading and downloading an image.

Add a new module that contain generic wrapper for file and iterator, which
are used to wrap image to upload and the request body iterator in upload and
download cases repectively, to show and advance a pretty progress bar when this
laters are consumed, The progress bar is triggered by adding a --progress command
line argument to commands: image-create, image-download or image-update.

Change-Id: I2ba42fd0c58f4fa087adb568ec3f08246cae3759
bug fix: LP#1112309
blueprint: progressbar-when-uploading

glanceclient/v2/shell.py

@@ -13,6 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from glanceclient.common import progressbar
 from glanceclient.common import utils
 from glanceclient import exc
 
@@ -125,9 +126,13 @@ def do_explain(gc, args):
                 'If this is not specified the image data will be '
                 'written to stdout.')
 @utils.arg('id', metavar='<IMAGE_ID>', help='ID of image to download.')
+@utils.arg('--progress', action='store_true', default=False,
+           help='Show download progress bar.')
 def do_image_download(gc, args):
     """Download a specific image."""
     body = gc.images.data(args.id)
+    if args.progress:
+        body = progressbar.VerboseIteratorWrapper(body, len(body))
     utils.save_image(body, args.file)