Add some devDependencies

Add grunt, grunt-nodemon and grunt-exec, as npm devDependencies;

Add the node_modules/ folder to the ignore list; Better organize the ignored files into groups.
Add the main project file
Init the Gruntfile

Add the first two tasks:
'default', who start the app thanks to the nodemon package.
'versioning' who start ungit for the version control system.
v0.0.2 release