Merge pull request #41 from Aevit/master

add audio (to do: change the length of the audio bubble according to the duration of the audio)
Roll back.
Fix multiple input type changes bug.

fix  https://github.com/xhzengAIB/MessageDisplayKit/issues/35
Change the file directory.
Add more controller class due with display message
Add more base controller class.
Change display controller super class.
Delete no use code.
Publish header to framework.
Fix the bug form input view layout frame.

fix https://github.com/xhzengAIB/MessageDisplayKit/issues/45
Update README.md
Update README.md
Update README.md
Update README.md
Support network photo and fix bug for tap the text

fix  https://github.com/xhzengAIB/MessageDisplayKit/issues/46

fix https://github.com/xhzengAIB/MessageDisplayKit/issues/47
fix the UIActivityIndicatorView bug.

fix https://github.com/xhzengAIB/MessageDisplayKit/issues/48
Add emotion gif message for example.
update podspec file v0.1.6
Update README.md
Add send videos message.

fix https://github.com/xhzengAIB/MessageDisplayKit/issues/54