🏗 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/util.py

@@ -1,5 +1,6 @@
 from __future__ import print_function
 
+import collections
 import io
 import logging
 import re
@@ -7,6 +8,7 @@ import subprocess
 import sys
 
 from esphome import const
+from esphome.py_compat import IS_PY2
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -153,3 +155,30 @@ def run_external_process(*cmd, **kwargs):
 
 def is_dev_esphome_version():
     return 'dev' in const.__version__
+
+
+# Custom OrderedDict with nicer repr method for debugging
+class OrderedDict(collections.OrderedDict):
+    def __repr__(self):
+        return dict(self).__repr__()
+
+    def move_to_end(self, key, last=True):
+        if IS_PY2:
+            if last:
+                # When moving to end, just pop and re-add
+                val = self.pop(key)
+                self[key] = val
+            else:
+                # When moving to front, use internals here
+                # https://stackoverflow.com/a/16664932
+                root = self._OrderedDict__root  # pylint: disable=no-member
+                first = root[1]
+                link = self._OrderedDict__map[key]  # pylint: disable=no-member
+                link_prev, link_next, _ = link
+                link_prev[1] = link_next
+                link_next[0] = link_prev
+                link[0] = root
+                link[1] = first
+                root[1] = first[0] = link
+        else:
+            super(OrderedDict, self).move_to_end(key, last=last)  # pylint: disable=no-member