Add library.json for platformio

See http://platformio.org for more information

library.json

+{
+  "name": "ESP8266_SSD1306",
+	"version": "3.0.0",
+  "keywords": "ssd1306, oled, display, i2c",
+  "description": "A I2C display driver for SSD1306 oled displays connected to an ESP8266",
+  "repository":
+  {
+    "type": "git",
+    "url": "https://github.com/squix78/esp8266-oled-ssd1306.git"
+  },
+	"authors":
+	[
+		{
+				"name": "Daniel Eichhorn",
+				"email": "squix78@gmail.com"
+		},
+    {
+        "name": "Fabrice Weinberg",
+        "email": "fabrice@weinberg.me"
+    }
+	],
+  "frameworks": "arduino",
+  "platforms": "espressif"
+}