OLINGO-434, OLINGO-435: Adding support to navigate Unary and Alias segements of parsed URL in UriParseTreeVisitor

Signed-off-by: mibo <mibo@apache.org>
[OLINGO-434] Fixed wrong MINUS position in Antlr file
[OLINGO-434] Added optional WSP between MINUS and property
[OLINGO-434][OLINGO-435] Merge branch 'Olingo-434-435'