Make sure nodejs plugin uses specified version of npm
currently the nodejs plugin uses bundled version of npm on linux/osx and the specified version of npm on windows. with the update of npm to 2.x version, it is not possible to download a package of npm with the version starting from 2.x (see https://github.com/npm/npm#windows-install-or-upgrade)
therefore the plugin should be enhanced to always use the specified version of npm regardless of the environment
fixed in 1ac6d76
if there is no nodejs installed, the plugin will download the packages version of node and npm for unix/linus environment. on windows it will download the specifeid node version and the latest available bundled npm version, which 1.4.9. in the next step it will install the specified npm version in the nodejs directory and use it for all subsequent executions of the npmInstall tasks.
thus it is guaranteed, that the specified npm version is used for the install task