util.isRootDir check for platforms/

platforms/ubuntu contains config.xml, so extra check is required
CB-5907 Make `cordova update` get version from platform's version script
Fix isWindows check in util.js to support win64
CB-5913 Fail more gracefully on Windows when symlinks fail.
Setting version to 3.3.1-0.3.0; updated plugman reference to 0.19.0
updated release notes
added firefoxos to readme
Setting version to 3.3.1-0.3.0; updated plugman reference to 0.19.0
updated release notes
updated to 3.4.0-rc.1
updated release notes
updated version file