Add a profile image picker to ProfileFragment

[aphexcx]

• When clicking the profile image in the Profile fragment, a choose image intent containing the camera and gallery as sources should pop up. This is the best library I found for this: http://stackoverflow.com/a/32475805/456568
• After image is chosen via camera or gallery, save it to the profileImage field on the user object.
• Make sure the user's profile image is displayed in the profile image, and if they don't have one, show the placeholder image.
• Bonus points for integrating lyft's scissors image cropping library after an image is chosen!