🏗 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/components/light/light_traits.h

@@ -0,0 +1,38 @@
+#pragma once
+
+namespace esphome {
+namespace light {
+
+/// This class is used to represent the capabilities of a light.
+class LightTraits {
+ public:
+  LightTraits() = default;
+
+  bool get_supports_brightness() const { return this->supports_brightness_; }
+  void set_supports_brightness(bool supports_brightness) { this->supports_brightness_ = supports_brightness; }
+  bool get_supports_rgb() const { return this->supports_rgb_; }
+  void set_supports_rgb(bool supports_rgb) { this->supports_rgb_ = supports_rgb; }
+  bool get_supports_rgb_white_value() const { return this->supports_rgb_white_value_; }
+  void set_supports_rgb_white_value(bool supports_rgb_white_value) {
+    this->supports_rgb_white_value_ = supports_rgb_white_value;
+  }
+  bool get_supports_color_temperature() const { return this->supports_color_temperature_; }
+  void set_supports_color_temperature(bool supports_color_temperature) {
+    this->supports_color_temperature_ = supports_color_temperature;
+  }
+  float get_min_mireds() const { return this->min_mireds_; }
+  void set_min_mireds(float min_mireds) { this->min_mireds_ = min_mireds; }
+  float get_max_mireds() const { return this->max_mireds_; }
+  void set_max_mireds(float max_mireds) { this->max_mireds_ = max_mireds; }
+
+ protected:
+  bool supports_brightness_{false};
+  bool supports_rgb_{false};
+  bool supports_rgb_white_value_{false};
+  bool supports_color_temperature_{false};
+  float min_mireds_{0};
+  float max_mireds_{0};
+};
+
+}  // namespace light
+}  // namespace esphome