Allow to specify port used by 'grunt server'

grunt will launch the server on port 5000 unless the env variable PORT is set.
Merge pull request #21 from avernois/define_port_use_by_grunt_server

Allow to specify port used by 'grunt server'
updated class to a more sexy way of creating classes in js
Merge pull request #22 from rhwy/localdatastorage_refactor

updated class to a more sexy way of creating classes in js