[add] Get the organizer information
[add] Get the user following organizers
[add] follow user (4 new api
[add] Like the post
[update] Search events

+ add keyword
+ add 搜尋我 follow (關注)的活動
+ add 搜尋朋友參加、follow (關注)的活動（`我朋友的活動`）
[update] get posts

add OAuth.
[update] follow 相關資源加上分頁
Merge pull request #4 from accuvally/requirements-change

Requirements change