Add MCP3008 I/O Expander (#1057)

* Add MCP3008

* Fixed Travis build issues

* Travis Build Fix

* Fix Travis foramt issues

* Travis fixes

* Code review changes

* Fix bit shift. off by one and selecting wrong pin

* general fixes

* lint

Co-authored-by: Guillermo Ruffino <glm.net@gmail.com>

esphome/components/mcp3008/sensor.py

@@ -0,0 +1,23 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import sensor
+from esphome.const import CONF_ID, CONF_NUMBER, CONF_NAME
+from . import mcp3008_ns, MCP3008
+
+DEPENDENCIES = ['mcp3008']
+
+MCP3008Sensor = mcp3008_ns.class_('MCP3008Sensor', sensor.Sensor, cg.PollingComponent)
+
+CONF_MCP3008_ID = 'mcp3008_id'
+
+CONFIG_SCHEMA = sensor.SENSOR_SCHEMA.extend({
+    cv.GenerateID(): cv.declare_id(MCP3008Sensor),
+    cv.GenerateID(CONF_MCP3008_ID): cv.use_id(MCP3008),
+    cv.Required(CONF_NUMBER): cv.int_,
+}).extend(cv.polling_component_schema('1s'))
+
+
+def to_code(config):
+    parent = yield cg.get_variable(config[CONF_MCP3008_ID])
+    var = cg.new_Pvariable(config[CONF_ID], parent, config[CONF_NAME], config[CONF_NUMBER])
+    yield cg.register_component(var, config)