force include_media_info to be true
Add include_media_info as a param default to true

From the dropbox API docs:

> include_media_info If true, each file will include a photo_info dictionary for photos and a video_info dictionary for videos with additional media info. If the data isn't available yet, the string pending will be returned instead of a dictionary.
Fixed comment typo

# for comment
force include_media_info to be false

From the dropbox API docs:

> include_media_info If true, each file will include a photo_info dictionary for photos and a video_info dictionary for videos with additional media info. If the data isn't available yet, the string pending will be returned instead of a dictionary.
Merge pull request #5 from SeanReid/master

Add include_media_info to `metadata`.  Thanks SeanReid!