Default to requiring frc namespace for wpilibc. (#972)

Instead of defining NAMESPACED_WPILIB to remove the "using namespace frc"
shim in Base.h, instead require NO_NAMESPACED_WPILIB be defined to add it.

Fix up various examples to use correct namespacing.

wpilibcExamples/src/main/cpp/examples/GearsBot/include/Subsystems/Wrist.h

@@ -15,7 +15,7 @@
  * The wrist subsystem is like the elevator, but with a rotational joint instead
  * of a linear joint.
  */
-class Wrist : public PIDSubsystem {
+class Wrist : public frc::PIDSubsystem {
  public:
   Wrist();