Second version of sharing button with new page and tests.

Query for users and their UserRecordAccess in one action rather than two steps.

![screen shot 2013-10-09 at 12 13 10 am](https://f.cloud.github.com/assets/2161427/1295565/48a240a8-30b2-11e3-9f30-93460ceda2c8.png)