Refactored Category model moving it to publication app so it can be reused in other apps
Creating newsletter app. First tests addressing #6.
Passing tests for newsletter and subscriptions
Merge branch 'newsletter', remote-tracking branch 'remotes/origin/newsletter' into development
Started file explorer app. Did the basic functions, but still need to find a way to upload the file to the server through tests. Was thinking about fixtures.
Moved category test to publication generic test. Implemented category in file explorer
Added todo about file post in file explorer
Merged in file-explorer (pull request #1)

Merging changes in Category and app file explorer
Added newsletter app in settings and holding #9
Created owner app
Refactored owner to own app and resolved #11
Did hierarchy in user and resolved #12
Altered depecrated declaration of Serializer
Merge remote-tracking branch 'origin/development' into development

Conflicts:
	publication/settings.py
	publication/urls.py
Created app user
Broken test to create children
Passed test to create user. Broken test for password when creating user
Refactored publication generic tests with functions always with the same signature
Passed test of hash in passwords when creating in user API
Finished basic tests in user app. Still need to create filter for owner to see just his sons data