Aligned plugin on latest Jenkins LTS
Added gitignore
Created NodeJSPlugin + NodeJS Installer
Allows to install NodeJS from nodejs.org - UI part only
Added nodeJSInstallationName on command interpreter
Transformed NodeJSCommandInterpreter from CommandInterpreter to Builder,
in order to have better flexibility over perform() method, allowing to download
ToolInstallation. Note that ATM, windows platform is not handled and
node version < 0.9.0 is not handled (archive structure is not the same)
Added test for InstallerPathResolver
Allows to check if every platform/cpu/versions generated installer url
exists
Not sorting installables in crawler
Prefering to sort them when retrieving installables
Installing npm packages when needed