🏗 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).

script/ci-custom.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python
+from __future__ import print_function
+
+import codecs
+import collections
+import os.path
+import sys
+
+
+def find_all(a_str, sub):
+    for i, line in enumerate(a_str.splitlines()):
+        column = 0
+        while True:
+            column = line.find(sub, column)
+            if column == -1:
+                break
+            yield i, column
+            column += len(sub)
+
+
+files = []
+for root, _, fs in os.walk('esphome'):
+    for f in fs:
+        _, ext = os.path.splitext(f)
+        if ext in ('.h', '.c', '.cpp', '.tcc', '.py'):
+            files.append(os.path.join(root, f))
+files.sort()
+
+errors = collections.defaultdict(list)
+for f in files:
+    try:
+        with codecs.open(f, 'r', encoding='utf-8') as f_handle:
+            content = f_handle.read()
+    except UnicodeDecodeError:
+        errors[f].append("File is not readable as UTF-8. Please set your editor to UTF-8 mode.")
+        continue
+    for line, col in find_all(content, '\t'):
+        errors[f].append("File contains tab character on line {}:{}. "
+                         "Please convert tabs to spaces.".format(line, col))
+    for line, col in find_all(content, '\r'):
+        errors[f].append("File contains windows newline on line {}:{}. "
+                         "Please set your editor to unix newline mode.".format(line, col))
+    if content and not content.endswith('\n'):
+        errors[f].append("File does not end with a newline, please add an empty line at the end of "
+                         "the file.")
+
+for f, errs in errors.items():
+    print("\033[0;32m************* File \033[1;32m{}\033[0m".format(f))
+    for err in errs:
+        print(err)
+    print()
+
+sys.exit(len(errors))