Update android-maven-gradle plugin version

Older version has issues if you are to use gradle 3.0. It would probably save some headache for people if they knew that they should use 1.5

Author: Jawnnypoo

build.gradle

@@ -5,8 +5,8 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.0.0'
-        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.3'
+        classpath 'com.android.tools.build:gradle:2.1.2'
+        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.5'
     }
 }