Pipeline whitelist

Add option so that users can opt not to see all newly created pipelines automatically.

![screen shot 2014-10-22 at 2 44 14 pm](https://cloud.githubusercontent.com/assets/24275/4745322/cff849ac-5a38-11e4-9406-e5a9b28186eb.png)

There is a new checkbox in the personalize pipelines dropdown called "Show newly created pipelines". Checking this will enable pipeline visibility whitelisting. If this is turned on the user will see only pipelines that they have opted into. Pipelines newly created by a user will be automatically added to their whitelist. Pipelines created by other users will not be automatically added to a user's whitelist.

Default behavior remains as it is today.