Add support to upload image from a local directory

When we create a new image to glance, we might get the
original image file from two place:
    1. copy from a URL
    2. upload a image file from users' own local directory.

This patch add support to upload a image file from users' local directory.

Change-Id: I17d1138c8442776b52feb4edf9da9d392c8abc4f