Fix build error with cordova-ios-4.x (backwards compatible)
Fix build error with cordova-ios-4.x (backwards compatible)

sxagan/ionic-plugin-keyboard,sxagan/ionic-plugin-keyboard,driftyco/ionic-plugin-keyboard,sxagan/ionic-plugin-keyboard,driftyco/ionic-plugin-keyboard,Telerik-Verified-Plugins/Keyboard,Telerik-Verified-Plugins/Keyboard,Telerik-Verified-Plugins/Keyboard,sxagan/ionic-plugin-keyboard,Telerik-Verified-Plugins/Keyboard,driftyco/ionic-plugin-keyboard,driftyco/ionic-plugin-keyboard