allow to override java command with environment variable JAVACMD

[hbriceno]

Hello,
On MacOSX (and any other system) sometimes one has multiple java versions.
It would be good to be able to override the "java" command easily.
I propose a tiny modification to do this:

diff --git a/lib/libCompiler.js b/lib/libCompiler.js
index b39ea00..9909473 100644
--- a/lib/libCompiler.js
+++ b/lib/libCompiler.js
@@ -56,7 +56,8 @@ compiler.validateFile = function validateFile( fileObj ) {
*/
compiler.compileCommand = function compileCommand( options, fileObj ) {

• var cmd = 'java ' +
• var javaCmd = process.env.JAVACMD || 'java';
• var cmd = javaCmd + ' ' +

This allows you to call
say you have a symlink java17 to a java 1.7 VM...
then you can call:

JAVACMD=java17 grunt...

request.