Update dependencies (#653)

* Update pio dependencies

* Platformio 4

* Fixes

* Update platformio_api.py

* Lint

esphome/components/async_tcp/__init__.py

@@ -0,0 +1,13 @@
+# Dummy integration to allow relying on AsyncTCP
+from esphome.core import CORE, coroutine_with_priority
+import esphome.codegen as cg
+
+
+@coroutine_with_priority(200.0)
+def to_code(config):
+    if CORE.is_esp32:
+        # https://github.com/me-no-dev/AsyncTCP/blob/master/library.json
+        cg.add_library('AsyncTCP', '1.0.3')
+    elif CORE.is_esp8266:
+        # https://github.com/me-no-dev/ESPAsyncTCP/blob/master/library.json
+        cg.add_library('ESPAsyncTCP', '1.2.0')