A6 A7 gateway (GSM GPRS) (#195)

* init 2G gateway with SMS sending and receiving

* A6lib add

* add 2Ggateway call from setup and loop

* add schematic and image

lib/A6lib/library.properties

@@ -0,0 +1,9 @@
+name=A6lib
+version=0.1.3
+author=Stavros Korokithakis
+maintainer=Stavros Korokithakis (hi@stavros.io)
+sentence=An ESP8266/Arduino library for communicating with the A6 GSM module.
+paragraph=
+category=Communication
+url=https://github.com/skorokithakis/A6lib
+architectures=*