Added a check for user roles in patching `/projects/:project`.

- Super is allowed everything.
Added proper restrictions for getting projects.

- Also refactored tests for better readability.
Began adding restrictions to updating the strings.
Added a new user-role for adding strings.
`strings-key` role are now required for deleting strings.
Refactored the tests for roles, to make them more concise and readable.
Merge branch 'master' into _roles

Conflicts:
	src/routes/strings.js
	test/helpers/index.js

Some tests are broken after the merge.
Updated roles to correctly restrict creating and deleting strings.

- There are no real support for translations yet.
Added end-point for getting all users.
Added an end-point for more easily updating all users.
Fixed a async-bug in the unit tests.
Fixed a buggy unit test.
Updated client-code to support associating users with roles in a project.
Added basic support for different user-roles per project.