Remove dead code from TopicsController
Remove dead code from TopicsController

The post creation from the #create route will no longer be used since we
are using the main discussion controller for new posts in video.

Signed-off-by: Shen Yichen <be3bb257ef8d73236feaba36cd3e5ee9095e6819@gmail.com>

Coursemology/coursemology2,cysjonathan/coursemology2,Coursemology/coursemology2,cysjonathan/coursemology2,Coursemology/coursemology2,cysjonathan/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2