Update gradle version, fix exception message

  Fixes #36
  Fixes #40

Author: samtstern

build.gradle

@@ -5,9 +5,9 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.1.3'
+        classpath 'com.android.tools.build:gradle:2.2.1'
 
-        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.4.1'
+        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.5'
         classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.7.1'
     }
 }

easypermissions/src/main/java/pub/devrel/easypermissions/EasyPermissions.java

@@ -294,7 +294,7 @@ private static void runAnnotatedMethods(Object object, int requestCode) {
                     // Method must be void so that we can invoke it
                     if (method.getParameterTypes().length > 0) {
                         throw new RuntimeException(
-                                "Cannot execute non-void method " + method.getName());
+                                "Cannot execute method " + method.getName() + " because it is non-void method and/or has input parameters.");
                     }
 
                     try {