upgrade to latest Datomic and Datomisca

Include explicit dependency on Datomisca, rather than assuming that
Play-Datomisca will bring in the right version.
improve DatomiscaAutoSource

- Solve read consistency. Make sure multiple reads within an action
are all using one consistency database value.
- General code cleaning.
improve DatomiscaAutoSourceController

- Abstract out the action builders in DatomiscaAutoSourceController.
This allows the user to override how `EssentialAction`s are built.
They can change all actions by overriding `defaultAction`, or they can
selectively handle each operation category: get, insert, update, and delete.
- Abstract out error handling for bad Json. Provide overridable helper
methods to handle bad requests.
- Clean up reader/writer implicits.
- Refactor helper methods for parsing query input hook into the bad
request mechanism rather than throw exceptions.
Merge pull request #19 from dwhjames/topic/datomisca

Improve Play Autosource for Datomisca