* Fix #1642, fix #1912 - Previous change (#1718) did not modify how original file was saved on upload

* Fix for when file is missing

* Custom Paperclip path.

* Document PAPERCLIP_ROOT.

* Add PAPERCLIP_ROOT_URL (and rename PAPERCLIP_ROOT to PAPERCLIP_ROOT_PATH).

add support for reading S3 protocol from ENV
also add S3_HOSTNAME in .env.production.sample

If an :original gets converted into another format, it would get saved as
original_filename *anyway*, so generating the extension is pointless and
yields bad results for when you change the style definition later. This way,
old gifs will still have correct URLs

for avatars/headers, resize avatars down to 120x120 instead of 300x300. Set cache headers on S3 stuff, also
make it private (aka only accessible via expiring links to prevent hotlinking)