Re-enable fem_system_ex2

Now that it's no longer relying on our old reinit() behavior, it
passes "make check" fine again.

Refs #1593.

examples/fem_system/fem_system_ex2/fem_system_ex2.C

@@ -154,9 +154,6 @@ int main(int argc, char ** argv)
   // Initialize libMesh and any dependent libraries
   LibMeshInit init(argc, argv);
 
-  libMesh::out << "This example is currently skipped due to changes in 3b4b2fb." << std::endl;
-  return 77;
-
   // This example requires a linear solver package.
   libmesh_example_requires(libMesh::default_solver_package() != INVALID_SOLVER_PACKAGE,
                            "--enable-petsc, --enable-trilinos, or --enable-eigen");