Fix INSTALLATION.md docs for v2.0.0 and Firebase Cloud Messaging (#1741)
Fix INSTALLATION.md docs for v2.0.0 and Firebase Cloud Messaging (#1741)


shazron/phonegap-plugin-push,jaraxasoftware/phonegap-plugin-push,phonegap/phonegap-plugin-push,phonegap/phonegap-plugin-push,intercom/phonegap-plugin-push,shazron/phonegap-plugin-push,jaraxasoftware/phonegap-plugin-push,intercom/phonegap-plugin-push,shazron/phonegap-plugin-push,phonegap/phonegap-plugin-push,jaraxasoftware/phonegap-plugin-push,intercom/phonegap-plugin-push