[#82700892] Admin can save DOI pattern & number for a journal

https://www.pivotaltracker.com/n/projects/880854/stories/82700892

self review feedback TODOs:
- [x] better names for publisher_prefix, journal_prefix, start_number
- [x] fix HTML labels.
- [x] cannot make two journals that do not have DOI info set (they are not uniquely blank)

— DT RW

![image](https://cloud.githubusercontent.com/assets/5796310/5080898/aa32a7ec-6e7b-11e4-8d38-fc3fc13f9420.png)

We pulled this factory from admin_journal_user_roles_test.js.coffee, and agree that an isolated Factory would improve this situation.  We've created a chore specifically for this.