started improved SPARQL implementation
Merge branch 'develop' of https://git-wip-us.apache.org/repos/asf/marmotta into sparql

Conflicts:
	libraries/kiwi/kiwi-sparql/src/main/java/org/apache/marmotta/kiwi/sparql/persistence/KiWiSparqlConnection.java
towards SPARQL native
library updates (Sesame, Guava, ...)
adapt to API changes in Guava
fix MARMOTTA-367 (OPTIONAL support) and MARMOTTA-494 (SPARQL builder)
implement support for ORDER BY (MARMOTTA-496)
first working implementation of MARMOTTA-536
implementation of MARMOTTA-536 (BIND) and a large number of additional functions for postgres
more SPARQL functions in native SQL (MARMOTTA-493)
first native implementation of GROUP BY (MARMOTTA-495)
some more aggregation functions
cleaning up the SPARQL->SQL translation
function cleanups (proper description of function parameters and return types)
variable cleanups (proper description of variable mappings between SPARQL and SQL)
first working UNION (MARMOTTA-538)
cover the case of UNION with BIND (MARMOTTA-538)
support subqueries in JOIN (MARMOTTA-538)
Merge branch 'develop' into ldp