added packer crawler for packer-plugin

packer.groovy

@@ -0,0 +1,28 @@
+#!./lib/runner.groovy
+// Generates server-side metadata for Packer auto-installation
+import com.gargoylesoftware.htmlunit.html.*;
+import com.gargoylesoftware.htmlunit.WebClient
+
+import com.gargoylesoftware.htmlunit.BrowserVersion
+
+import net.sf.json.*
+
+BrowserVersion browserVer = BrowserVersion.getDefault()
+def wc = new WebClient(browserVer)
+def baseUrl = 'http://dl.bintray.com/mitchellh/packer'
+HtmlPage p = wc.getPage(baseUrl);
+
+def json = [];
+
+p.selectNodes("//a[@href]").reverse().collect { HtmlAnchor e ->
+    def href = e.getHrefAttribute().replaceFirst(/^#/) {''}
+    def url = baseUrl + "/" + href
+    //println url
+    def m = (url =~ /.*(\d+.\d+.\d+)_(.*)_(.*).zip/)
+    if (m) {
+        def verId = "${m[0][1]}-${m[0][2]}-${m[0][3]}".toString()
+        json << ["id": verId, "name": "Packer ${m[0][1]} ${m[0][2]} (${m[0][3]})".toString(), "url": url];
+    }
+}
+
+lib.DataWriter.write("biz.neustar.jenkins.plugins.packer.PackerInstaller",JSONObject.fromObject([list:json]));