Dynamo start page URL updates

This pull request accomplishes two things:

- Updated ```REFERENCES``` section of start page to the right URLs
- Disable start page if Dynamo was launched in playback mode (e.g. ```/c``` command flag)

It fixes the following defects tracked internally:

- [MAGN-3856](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-3856) Start page shouldn't show up during playback
- [MAGN-3852](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-3852) Reference links in start page should be updated