This worked:
-keep public class * extends com.phonegap.api.Plugin
-keep public class * extends org.apache.cordova.api.Plugin
-keep public class org.apache.cordova.DroidGap
-keep public class org.apache.cordova.**
-keep public class org.apache.**
-dontwarn android.webkit.*
-dontwarn org.apache.**
-keep public class * extends org.apache.cordova.api.CordovaPlugin
-keep class org.apache.cordova.** { *; }