wip add coffer_http_storage handler

add intial storage cowboy handler to list and upload blobs using the
multipart API.

TODO:
- storage server to initialise and maintain the storage config
- coffer_blobserver_localdisk module to store the blobs on the localdisk
fix reader function
wip .
fix tests
fix the order we get the properties
add release support and coffer_http
use deps
don't rename file and only use rebar to handle the code

lager doesn't works so well with the scope feature from reltool_utils so
rather than hacking around let just remove for now the namespace
handling. We don't have really a use for it anyway until people try to
extend the coffer release with their own dependencies.

while I'm here fix the release boot.
back to the normality, warn if we use a deprecated function

Patched cowboy to use the right SHA function on Erlang R16 and R17 so we
can reactivate the check on deprecated functions.
fix coffr_http_storages handler
handle most blob and storages actions:

* blobs actions

- GET /<storage> : list blobs in the storage, limit as optional
  parameter
- POST /<storage> MULTIPART BODY : upload multiple blobs
- HEAD /<storage>/<blobref> : return 200 if the blob exists, 404 not
  found
- GET /<storage>/<blobref> : stream the blob to the client
- PUT /<storage>/<blobref> : upload a blob
- DELETE /<storage>/<blobref> : delete a blob

* storages

GET /storages : list all storages available