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)

![start-page-reference](https://cloud.githubusercontent.com/assets/5086849/3465569/e4b2cc50-0268-11e4-9932-50765de46f5b.png)

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

Hi @aparajit-pratap and @elayabharath, since you guys are closer to this, could you help me to review it? Thanks :)