replaced 'patch it' with 'patch latest' and 'patch first' with 'patch given' for behave tests
'... delete latest' instead of 'delete it'
doc(readme): how to run in production initial desc

add info how to run server via gunicorn
fix(config): change how amazon storage gets enabled

instead of just checking if this config exists it now always reads
os.env and checks if the value is not none

SD-381
refactor(app): change the way how domain is registered

introduce `init_app` method in app modules which will get called when
a new app is being created via `get_app` factory
fix(domain): register resources defined via superdesk.domain
fix(celery): setup celery.Task only once