Version bump for 2.0.0

Makefile

 #!/usr/bin/make -f
 
-MAJOR := 1
-MINOR := 3
+MAJOR := 2
+MINOR := 0
 PATCH := 0
 VERSION := $(MAJOR).$(MINOR).$(PATCH)
 PREFIX ?= /usr/local

javascript/package.json

 {
   "name": "olm",
-  "version": "1.3.0",
+  "version": "2.0.0",
   "description": "An implementation of the Double Ratchet cryptographic ratchet",
   "main": "olm.js",
   "files": [