DMAP-45 - Prepare BrowserMap module for ASF releases

* removed redundant development dependencies
* updated README - jscoverage does not need to be installed globally

git-svn-id: https://svn.apache.org/repos/asf/incubator/devicemap/trunk/browsermap/trunk@1611399 13f79535-47bb-0310-9956-ffa450edef68