SES-1808 : Add Virtuoso Geometry datatype handler

This handler is necessary to parse DBPedia data successfully with
datatype verification and fail-on-unknown-datatypes active.
SES-1808 : Cleanup imports
SES-1808 : Add virtuoso geometry to default datatype handlers
SES-1808 : Make datatype and language handler initialization less likely
to cause class initialization failures
SES-1808 : Add null checks for cases where the handler is not found
SES-1815 added Runtime shutdownhook for internal repository shutdown
SES-1815 gave thread a name.
SES-1815 implemented by simply overriding Servlet.destroy().
SES-1815 removed unused imports
Merged in ses-1815 (pull request #125)

SES-1815 workbench should shutdown local query store on destroy
SES-1808 : Add logging for failures loading datatype and language
handlers
SES-1808 : Add stub test for DatatypeHandler interface
SES-1808 : Initial implementation of abstract datatype handler tests
SES-1808 : Add datatypes and languages dependencies to rio-compliance
SES-1808 : Make values non-optional for verify

With optional values, the verify may miss null values that it should
highlight, and it is otherwise no more than a check on whether the URI
is recognised
SES-1808 : Add more strictness for NPEs
SES-1808 : Tests must be able to be overriden to be ignored

Some datatype handlers need to be able to ignore specific tests if there
are no invalid values
SES-1808 : Add datatype handler tests for RDF LangString and XSD Double
SES-1808 : Fix comments
SES-1808 : Add DBPedia Celsius test

None of the DBpedia datatypes are verified or normalised, other than
checking they start with the uniform prefix