Set sourceCompatibility and targetCompatibility

Author: immortius

config/gradle/common.gradle

@@ -8,6 +8,9 @@ apply plugin: 'checkstyle'
 apply plugin: 'pmd'
 apply plugin: 'findbugs'
 
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
+
 // We use both Maven Central and our own Artifactory instance, which contains module builds, extra libs, and so on
 repositories {
     mavenCentral()