Update code for OS detection on Mac OS X (tufts.Util:164)

[mariusid]

Hello VUE team,

First of all, thank you very much for this wonderful tool!
As I don't know (yet, I hope :-) ) how to provide patches on GitHub, I am just describing the problem.

Please change the call to get the version of the Mac OS X as by default it ends up with a NPE if using Oracle JRE.

In tufts.Util.java line 164:
String mrj = System.getProperty("mrj.version");
should be changed so that "os.name" instead of the old "mrj.version" property.

Otherwise, here is the result (debug flag included for details):

$ java -Dtufts.Util.debug=1 -jar VUE_3.2.2.jar
tufts.Util: Platform: Mac OS X / 10.9.1 / x86_64
tufts.Util: Java Version: 1.7; JVM-bits=64; 64bit=true
tufts.Util: Mac OS X major version number (float): 10.9
tufts.Util: Mac Leopard (10.5) or later = true
Exception in thread "main" java.lang.ExceptionInInitializerError
at tufts.vue.VueResources.(VueResources.java:194)
at tufts.vue.SearchTextField.(SearchTextField.java:88)
at tufts.vue.VUE.(VUE.java:175)
Caused by: java.lang.NullPointerException
at tufts.Util.(Util.java:166)
... 3 more
$

I am using the latest (available version at the time of this writing) JRE from Oracle:

$ java -version
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)
$

Currently, since I am using a Mac Book Pro with Retina display (and support for Retina is provided starting with Java 7 Update 40), I am running VUE 3.2.2 using the following command (to get rid of the NPE):
java -Dmrj.version=10.9 -jar VUE_3.2.2.jar

Thanks