Custom form validations

Hey @devcritter . Do you mind just reviewing this PR for me. It originally related to issue https://github.com/jembi/openhim-console/issues/56 but after some investigation and trails I figured that our forms will work much better with custom validation. This resolves all issues we had before and any new validation can be added easily.

Its also in the back of my head to convert these validations into an Angular factory for better re-use which ill look at when there are less pressing issues.
typo: once -> one