light: Added light sensor C source

Added the C source for the light sensor with necessary changes to cmake,
examples, docs.

    * Renamed all files with grovelight to light
    * Replaced all instances of grovelight with light
    * Added C source for light sensor
    * Updated all cmake files
    * Added C example for light sensor
    * Split out light sensor from grove library

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/light/light.hpp

@@ -0,0 +1,92 @@
+/*
+ * Authors: Brendan Le Foll <brendan.le.foll@intel.com>
+ *          Mihai Tudor Panu <mihai.tudor.panu@intel.com>
+ *          Sarah Knepper <sarah.knepper@intel.com>
+ * Copyright (c) 2014 - 2016 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+#include <string>
+#include <mraa/aio.hpp>
+
+namespace upm {
+
+/**
+ * @library light
+ * @sensor light
+ * @comname  Light Sensor
+ * @type light
+ * @man seeed
+ * @con analog
+ * @kit gsk
+ *
+ * @brief API for the  Light Sensor
+ *
+ * The  light sensor detects the intensity of the ambient light.
+ * As the light intensity of the environment increases, the resistance
+ * of the sensor decreases. This means the raw value from the
+ * analog pin is larger in bright light and smaller in the dark.
+ * An approximate lux value can also be returned.
+ *
+ * @image html light.jpg
+ * @snippet light.cxx Interesting
+ */
+class Light {
+    public:
+        /**
+         *  analog light sensor constructor
+         *
+         * @param pin Analog pin to use
+         */
+        Light(unsigned int pin);
+        /**
+         * Light destructor
+         */
+        ~Light();
+        /**
+         * Gets the raw value from the AIO pin
+         *
+         * @return Raw value from the ADC
+         */
+        float raw_value();
+        /**
+         * Gets an approximate light value, in lux, from the sensor
+         *
+         * @return Normalized light reading in lux
+         */
+        int value();
+
+        /* Sensor name
+         *
+         * @return Sensor name
+         */
+        std::string name()
+        {
+            return m_name;
+        }
+
+    private:
+        mraa_aio_context m_aio;
+        const std::string m_name = "Light Sensor";
+};
+}