Copter: ask for IMU samples at 100Hz

this produces the same result, but makes things simpler in the driver

ArduCopter/ArduCopter.pde

@@ -170,7 +170,7 @@ static DataFlash_Empty DataFlash;
 ////////////////////////////////////////////////////////////////////////////////
 // the rate we run the main loop at
 ////////////////////////////////////////////////////////////////////////////////
-static const AP_InertialSensor::Sample_rate ins_sample_rate = AP_InertialSensor::RATE_200HZ;
+static const AP_InertialSensor::Sample_rate ins_sample_rate = AP_InertialSensor::RATE_100HZ;
 
 ////////////////////////////////////////////////////////////////////////////////
 // Sensors
@@ -937,7 +937,7 @@ void loop()
 
     // We want this to execute fast
     // ----------------------------
-    if (ins.num_samples_available() >= 2) {
+    if (ins.num_samples_available() >= 1) {
 
         // check loop time
         perf_info_check_loop_time(timer - fast_loopTimer);