adding new follow target parameter

src/modules/navigator/follow_target_params.c

@@ -0,0 +1,55 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2016 PX4 Development Team. All rights reserved.
+ *
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+
+/**
+ * @file follow_target_params.c
+ *
+ * Parameters for follow target mode
+ *
+ * @author Jimmy Johnson <catch22@fastmail.net>
+ */
+
+/*
+ * Follow target parameters
+ */
+
+/**
+ * Minimum follow target altitude
+ *
+ * The minimum height in meters relative to home for following a target
+ *
+ * @unit meters
+ * @min 8.0
+ * @group Follow target
+ */
+PARAM_DEFINE_FLOAT(NAV_MIN_FT_HT, 8.0f);