Change format of the screenshot filename

Previous images were named in the following manner
```
{EVERGREEN|PINNED}_browsername_version_platform
```
Now the are named
```
{EVERGREEN|PINNED}_platform_browsername_VERSION_version
```

This was done so that detecting similar evergreens was easier.

script/screenshots.js

diff --git a/script/screenshots.js b/script/screenshots.js
index e011e49..e88dd12 100644
--- a/script/screenshots.js
+++ b/script/screenshots.js
@@ -84,9 +84,9 @@
   browserDriver.init(cfg, function(err, _, capabilities) {
     if (err) console.log(err);
 
-    var browser = obj.pinned+'_'+cfg.browserName.replace(/\s/g, '_')+(capabilities ? '_'+capabilities.version : '');
+    var browser = cfg.browserName.replace(/\s/g, '_')+(capabilities ? '_VERSION'+capabilities.version : '');
     var platform = (capabilities || cfg).platform.replace(/\s/g, '_');
-    var piecesDir = allImgsDir+'/'+browser+'_'+platform;
+    var piecesDir = allImgsDir+'/'+obj.pinned+'_'+platform+'_'+browser;
     fs.mkdirSync(piecesDir);
 
     browserDriver.get(url, function(err) {