[OCaml] Rename example_prog.ml to runme.ml in the OCaml examples

Name the output executable "runme" in the examples.
Replace use of "foolib" in the string_from_ptr example.
Fix a warning in the std_vector example.
Add strings_test to Examples/ocaml/check.list.
Disable two tests that were causing the OCaml test suite to fail.

Examples/ocaml/contract/Makefile

@@ -5,7 +5,7 @@ SRCS       =
 TARGET     = example
 INTERFACE  = example.i
 MLFILE     = example.ml
-PROGFILE   = example_prog.ml
+PROGFILE   = runme.ml
 OBJS       =
 
 check: build