Hagrid upgrade to v2 (#5)

* Refactor backend with beego framework

* Add tcpService module

* Refactor syncing alert

* Temp save

* Add modal and button class

* Temp save frontend codes

* Temp save async actions

* Finish Update/Add graphite modal

* Make the table more stable and beautiful

* Add a select for alerts

* Add and finish TCPService module

* Almost finish template module

* Use select2 as tagInput

* Finish templates and adjust some styles

* Finish user profile page

* Finish add alert page

* Finish update alert page

* Finsh admin management

* Finish notifier

* Update icinga image and fix some bugs

* Remove strict phone number validaton

* Refactor error message output

* Fix serval bugs

- Fix logout failed causing by cookie.
- Automatically choose first alert after login if one exists.
- Remove href attribute from <a> tags and add a pointer cursor style.
- Add HelpCard but with empty content.

* Finish help page

* Remove alpha verison

* Add a health check API

* Fix frontend bug

- Fix: The selected alert is back to the default after saving

* Add check_http module

- Remove redudant and compress js files
- Format files
- Update icinga2 base image

* Fix issue of rendering template

* Add the link for check_http manual

* Fix text error

* Fix bug of rendering post data field of check_http