Update Gemfile (in particular rdf 1.0)

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Refactoring of repository_spec to remove deprecated messages

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Optimize insert_statements

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Enhance #raw_query :
* add options support (:infer and :format)
* autoselect the format depending of the query type (construct/select)
* add yield support

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Add Repository#sparql_query

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Add context storing that will be used for each query

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>