🏗 Merge C++ into python codebase (#504)

## Description:

Move esphome-core codebase into esphome (and a bunch of other refactors). See https://github.com/esphome/feature-requests/issues/97

Yes this is a shit ton of work and no there's no way to automate it :( But it will be worth it 👍

Progress:
- Core support (file copy etc): 80%
- Base Abstractions (light, switch): ~50%
- Integrations: ~10%
- Working? Yes, (but only with ported components).

Other refactors:
- Moves all codegen related stuff into a single class: `esphome.codegen` (imported as `cg`)
- Rework coroutine syntax
- Move from `component/platform.py` to `domain/component.py` structure as with HA
- Move all defaults out of C++ and into config validation.
- Remove `make_...` helpers from Application class. Reason: Merge conflicts with every single new integration.
- Pointer Variables are stored globally instead of locally in setup(). Reason: stack size limit.

Future work:
- Rework const.py - Move all `CONF_...` into a conf class (usage `conf.UPDATE_INTERVAL` vs `CONF_UPDATE_INTERVAL`). Reason: Less convoluted import block
- Enable loading from `custom_components` folder.

**Related issue (if applicable):** https://github.com/esphome/feature-requests/issues/97

**Pull request in [esphome-docs](https://github.com/esphome/esphome-docs) with documentation (if applicable):** esphome/esphome-docs#<esphome-docs PR number goes here>

## Checklist:
  - [ ] The code change is tested and works locally.
  - [ ] Tests have been added to verify that the new code works (under `tests/` folder).

If user exposed functionality or configuration variables are added/changed:
  - [ ] Documentation added/updated in [esphomedocs](https://github.com/OttoWinter/esphomedocs).

esphome/wizard.py

@@ -7,7 +7,6 @@ import unicodedata
 import voluptuous as vol
 
 import esphome.config_validation as cv
-from esphome.const import ESP_PLATFORMS, ESP_PLATFORM_ESP32, ESP_PLATFORM_ESP8266
 from esphome.helpers import color, get_bool_env
 # pylint: disable=anomalous-backslash-in-string
 from esphome.pins import ESP32_BOARD_PINS, ESP8266_BOARD_PINS
@@ -177,7 +176,7 @@ def wizard(path):
         safe_print("Please enter either ESP32 or ESP8266.")
         platform = safe_input(color("bold_white", "(ESP32/ESP8266): "))
         try:
-            platform = vol.All(vol.Upper, vol.Any(*ESP_PLATFORMS))(platform)
+            platform = vol.All(vol.Upper, vol.Any('ESP32', 'ESP8266'))(platform)
             break
         except vol.Invalid:
             safe_print(u"Unfortunately, I can't find an espressif microcontroller called "
@@ -186,7 +185,7 @@ def wizard(path):
     safe_print()
     sleep(1)
 
-    if platform == ESP_PLATFORM_ESP32:
+    if platform == 'ESP32':
         board_link = 'http://docs.platformio.org/en/latest/platforms/espressif32.html#boards'
     else:
         board_link = 'http://docs.platformio.org/en/latest/platforms/espressif8266.html#boards'
@@ -194,11 +193,11 @@ def wizard(path):
     safe_print("Next, I need to know what " + color('green', 'board') + " you're using.")
     sleep(0.5)
     safe_print("Please go to {} and choose a board.".format(color('green', board_link)))
-    if platform == ESP_PLATFORM_ESP8266:
+    if platform == 'ESP32':
         safe_print("(Type " + color('green', 'esp01_1m') + " for Sonoff devices)")
     safe_print()
     # Don't sleep because user needs to copy link
-    if platform == ESP_PLATFORM_ESP32:
+    if platform == 'ESP32':
         safe_print("For example \"{}\".".format(color("bold_white", 'nodemcu-32s')))
         boards = list(ESP32_BOARD_PINS.keys())
     else: