Add MPR121 Capacitive Touch Sensor (#449)

* module mpr121

* added mpr121 sensor and binary sensor

* added tests

* removed CONF_CHANNELS, it is not supported in the esphome-code mpr121
code

* changed namespace for mpr121 to binary_sensor

* Update esphome/components/binary_sensor/mpr121.py

Co-Authored-By: mvturnho <qris.online@gmail.com>

* fixed class names

* fix lint errors

esphome/components/binary_sensor/mpr121.py

@@ -0,0 +1,28 @@
+import voluptuous as vol
+
+from esphome.components import binary_sensor
+from esphome.components.mpr121 import MPR121Component, CONF_MPR121_ID
+import esphome.config_validation as cv
+from esphome.const import CONF_CHANNEL, CONF_NAME
+from esphome.cpp_generator import get_variable
+
+DEPENDENCIES = ['mpr121']
+MPR121Channel = binary_sensor.binary_sensor_ns.class_(
+    'MPR121Channel', binary_sensor.BinarySensor)
+
+PLATFORM_SCHEMA = cv.nameable(binary_sensor.BINARY_SENSOR_PLATFORM_SCHEMA.extend({
+    cv.GenerateID(): cv.declare_variable_id(MPR121Channel),
+    cv.GenerateID(CONF_MPR121_ID): cv.use_variable_id(MPR121Component),
+    vol.Required(CONF_CHANNEL): vol.All(vol.Coerce(int), vol.Range(min=0, max=11))
+}))
+
+
+def to_code(config):
+    for hub in get_variable(config[CONF_MPR121_ID]):
+        yield
+    rhs = MPR121Channel.new(config[CONF_NAME], config[CONF_CHANNEL])
+    binary_sensor.register_binary_sensor(hub.add_channel(rhs), config)
+
+
+def to_hass_config(data, config):
+    return binary_sensor.core_to_hass_config(data, config)