Removed deprecated AARLinkSources plugin

As per their documentation, AS 1.4+ automatically supports it,
so it's no longer necessary. (Plus, it blows up newer versions of
Gradle.)

Habitica/build.gradle

@@ -1,6 +1,5 @@
 apply plugin: 'com.android.application'
 apply plugin: 'com.android.databinding'
-apply plugin: 'aar-link-sources'
 apply plugin: 'io.fabric'
 
 buildscript {

build.gradle

@@ -3,19 +3,11 @@
 buildscript {
     repositories {
         jcenter()
-        //Plugin to download sources on a fake maven github repo
-        maven { url 'https://raw.github.com/xujiaao/mvn-repository/master/releases' }
-
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:1.3.0'
         classpath 'com.android.databinding:dataBinder:1.0-rc1'
-
-        //Class path for the plugin to auto download sources
-        classpath 'com.github.xujiaao:aarLinkSources:1.0.0'
-
         classpath 'com.neenbedankt.gradle.plugins:android-apt:1.4'
-
     }
 }