remove unnecessary return statement inside Discourse.Router.map

Ember's Router.map(callback) method doesn't expect any value to be
returned by callback function. Therefore, return statements present
inside Discourse.Router.map are unnecessary (and are silently ignored by
Ember).
Remove duplicate create method in PostCreator
adds unit tests for Discourse.Model
Merge pull request #1472 from velesin/model_tests

adds unit tests for Discourse.Model
Merge pull request #1451 from velesin/remove_return_from_router_map

remove unnecessary return statement inside Discourse.Router.map
allow users to specify thumbnail size
German typo fix
Merge pull request #1474 from jhilden/patch-1

German typo fix
Merge pull request #1458 from thomas-mcdonald/remove-duplicate-method

Remove duplicate create method in PostCreator
Merge branch 'master' of https://github.com/discourse/discourse
Merge branch 'master' of github.com:rux-pizza/discourse