Updates to Demographics Display

- Gating on feature enabled for Open edX users
- If feature disabled and Insights URL is set, displaying message pointing users to Insights

![screen shot 2014-10-29 at 12 18 44 pm](https://cloud.githubusercontent.com/assets/910510/4829788/2fea4db0-5f89-11e4-861b-6f1f961155cb.png)


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