Bump schema salad version dep to 1.17.

Author: Peter Amstutz

setup.py

@@ -41,7 +41,7 @@
           'rdflib >= 4.1.0',
           'rdflib-jsonld >= 0.3.0',
           'shellescape',
-          'schema-salad==1.16.20160819133325',
+          'schema-salad==1.17.20160820165726',
           'typing' ],
       test_suite='tests',
       tests_require=[],