Converted ShatteredPD to Build from Gradle

Major Changes:
- Shattered now builds effortlessly either from gradle CLI or android studio
- Much better dependency management through gradle (although it's not really used atm)
- Separate PD-classes repo is now SPD-classes module within main repo

core/build.gradle

@@ -0,0 +1,17 @@
+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 23
+    buildToolsVersion "24.0.0"
+
+    buildTypes {
+        release {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+}
+
+dependencies {
+    compile project(':SPD-classes')
+}