changed -Xmx2g to -Xmx512m when invoking JVM to run minall task. See angular#4595

Author: MJRichardson

lib/grunt/utils.js

@@ -378,7 +378,7 @@ module.exports = {
     shell.exec(
         'java ' +
             this.java32flags() + ' ' +
-            '-Xmx2g ' +
+            '-Xmx512m ' +
             '-cp bower_components/closure-compiler/compiler.jar' + classPathSep +
             'bower_components/ng-closure-runner/ngcompiler.jar ' +
             'org.angularjs.closurerunner.NgClosureRunner ' +