refine header switches style
mock up msg form

- Add bulletin service/controller, msg form
- refactor form styles
- refactor form html markup
- fix style bug in firefox
basic bulletin
add enrollments ui
Teacher enrollments

- refactor styles
- support teacher in group enrollment crud
- fix flowjs flow.js issue, need check
Merge pull request #11 from Bratops/0.1.8_bulletin_system

manager bulletin, teacher groups and enrollment