Oops should be version not build

Former-commit-id: 0ed5cfc3e56b464e971a1ecf4d6304aba1cc682d
Former-commit-id: 4c59f251dafe8b6d3ab1e5d86dbaf74af5bd7fad
Former-commit-id: 235c036765afccd2818c950dbae8205c243fc33e

build/aspnet5-version.js

@@ -2,7 +2,7 @@
 var util = require('util');
 
 var file = '../src/imageprocessor/project.json';
-var buildNumber = process.env.APPVEYOR_BUILD_NUMBER;
+var buildNumber = process.env.APPVEYOR_BUILD_VERSION;
 
 jsonfile.readFile(file, function (err, project) {
     project.version = buildNumber;