Setup for heroku.
Remove demo posts.
Enable pygments for syntax highlighting.
Add posts for Tags related APIs.
Add posts for account related APIs.

* Update user profile.
* Signup
* Get credential token.
Update posts of Response codes.
Add authentication posts for signin related APIs.
Remove google fonts.
Add posts for Group related APIs.
Fix typo of creating new tag.
Add posts for friends related APIs.
Update APIs sorting.
Fix authentication APIs.
Add posts of comments releated APIs.
Add posts for like related APIs.
Add posts for release note of v0.1.
Add posts for overview.
Add posts of media related APIs.
Add posts of starter_guide.
Add instructions for installing postgresql.