Handle query string when parsing data format

URLs may contain a query string (prefixed with '?') and this should be ignored when parsing
the data format.

To facilitate testing this functionality, ParseDataFormat has been made non-static.

src/Makefile.test.include

@@ -116,6 +116,7 @@ BITCOIN_TESTS =\
   test/prevector_tests.cpp \
   test/raii_event_tests.cpp \
   test/random_tests.cpp \
+  test/rest_tests.cpp \
   test/reverselock_tests.cpp \
   test/rpc_tests.cpp \
   test/sanity_tests.cpp \