Add provided scope on the API
Fix #47 : color resetting
Fix #48 : add ctrl+d, shutdown command for exiting CLI
#3 Setup a file credential store

CachedFileCredntialsStore gives a way to store crendentials on the
filesytem, keeping a in-memory cache for all get operations.
#3 Store token in the login command

User CachedFileCredentialsStore to store the token in the login
command. Also make CachedFileCredentialsStoreFactory a singleton to
ensure unicity of the DataStores.