Media upload

[shaheinm]

Resolves #27

New Environment variable required

• REACT_APP_MEDIA_SERVICE_ENDPOINT

To upload an image:

• Click on the + image in the media gallery thumbnails
• Drag & drop an image, or click the drag and drop area and select one, to the outlined area on the modal
• A progress circle will appear while the image is being processed
• When the upload is finished, the image link will appear as a chip below
• Select "Submit" to add the link to the media gallery
• You can also paste links in the text field, comma delimited
• Uploading multiple files works, it sends each file individually, so it may take some time.

There are also some updates to the home/landing page (and login is now a modal) to reflect some of the changes made here: https://projects.invisionapp.com/share/C2XCDX14NWK#/screens/421513821