Handle composition and persistence of custom fields

Allow special handling of serialization/deserialization of custom fields
such as datetime. For example in MongoDB, datetime can be persisted natively as
datetime.datetime. But conversely, datetime needs to be stringify
before persisting in Couchbase.
Setup for persistence layer

Implement setup methods in persistence drivers to create appropriate
indices and views for resource models.
Merge branch 'master' of github.com:m4dcoder/raiden