use WPILIB eclipse var & use luna to build

Change-Id: I5e8560329226fca3c60f337b6b4744c50a09cdc9

eclipse-plugins/edu.wpi.first.wpilib.plugins.core/META-INF/MANIFEST.MF

@@ -22,7 +22,8 @@ Require-Bundle: org.eclipse.ui,
  org.eclipse.ui.navigator.resources;bundle-version="3.4.400",
  org.eclipse.ui.intro,
  org.eclipse.ui.intro.universal,
- org.eclipse.core.expressions;bundle-version="3.4.400"
+ org.eclipse.core.expressions;bundle-version="3.4.400",
+ org.eclipse.core.variables;bundle-version="3.2.700"
 Bundle-ActivationPolicy: lazy
 Bundle-RequiredExecutionEnvironment: JavaSE-1.7
 Export-Package: edu.wpi.first.wpilib.plugins.core,

eclipse-plugins/edu.wpi.first.wpilib.plugins.core/plugin.xml

@@ -83,5 +83,14 @@
             content="WPILib Intro/sample.xml">
       </configExtension>
    </extension>
+   <extension
+         point="org.eclipse.core.variables.valueVariables">
+          <variable
+    name="WPILIB"
+    initialValue="${HOME}/wpilib"
+    description="WPILib Path"
+    >
+   </variable>
+   </extension>
 
 </plugin>