test cases for announcement creation and editing
add type for describe
more tests for announcement editing
change expiry_at to parameters
[testing] add controller test helper
fix typo in course model
[testing] move mission page test to features test dir
Merge pull request #268 from wangqiang1208/test/hackathon-tests

test cases for announcement creation and editing
Merge branch 'development' of github.com:Coursemology/coursemology.org into development