OGM-264 Don't expose JDBC-related IntegralDataTypeHolder via GridDialect#nextValue()

* Changing the method to expect a parameter object, simplifying further evolution
* Returning the sequence value, hiding the usage of IntegralDataTypeHolder from grid dialects
OGM-445 Moving several services to the standard registry; Replacing StartStoppable contract by SchemaInitializer contract

* Making DatastoreProvider, OptionsService and TypeTranslator services in the standard registry
* SchemaInitializer implementations are invoked via a SF listener after bootstrapping and obtain a fully set-up session factory
* Moving DatastoreProvider to the standard registry allows to do the same for GridDialect which will make it usable at more places
OGM-445 Making GridDialect a service in the standard registry
OGM-445 Exposing GridDialect via OGM Dialect, retrieving it from there in generators
OGM-445 Implementing design document creation and entity mapping sanity check in CouchDB as schema initializer
OGM-445 Implementing sequence generator validation in MongoDB via SchemaInitializer contract
OGM-445 Initializing sequences in Neo4j via SchemaInitializer rather than a custom integrator
OGM-445 Marking SchemaInitializer contract as experimental