Fixes mockito#765: Set files encoding to UTF-8 to avoid build failure…

…s on systems with different default encoding (mockito#780)

build.gradle

@@ -39,6 +39,7 @@ allprojects {
     tasks.withType(JavaCompile) {
         //I don't believe those warnings add value given modern IDEs
         options.warnings = false
+        options.encoding = 'UTF-8'
     }
 }