Upgrade to the Spring Data Dijkstra release train

In addition to the upgrade to Dijkstra (#743) Spring HATEOAS has been
upgraded to 0.11.0 (#801) and Mongo's Java driver has been upgraded to
2.12.1 (#689). In both cases this is the same version as is used by
Dijkstra RC1.

The new version of Mongo's Java driver changes the exception that's
thrown when Mongo isn't running and a connection attempt fails. The
Mongo sample has been updated accordingly.

RepositoryRestMvcAutoConfiguration has been updated to be configured
before JpaRepositoriesAutoConfiguration. This ensures that the
former's transitive import of SpringDataJacksonConfiguration takes
precedence over the latter's import of the same. This is necessary as
RepositoryRestMvcConfiguration requires a bean that's declared by
SpringDataJacksonConfiguration and, if JpaRepositoriesAutoConfiguration
is processed first, its conditions may cause the import
SpringDataJacksonConfiguration to be skipped causing instantiation
of RepositoryRestMvcConfiguration to fail.

Closes #689
Closes #743