Resolve "comment creation - creator component logic"

Information

• created comment service (add comment function http)
• added logic components to create-comment (send button function, back button function)
• added simple routing

Missing

• comment id is not considered
• variables revision, read are not considered

Testing

• check code quality
• check functionality
• checkout page with http://localhost:4200/room/test/create-comment
• for output of comment, add console.log(comment) to service comment

Closes #41 (closed) Closes #27 (closed)