Added rules config methods

[dctoon]

Added support for the Rules Configs endpoints.

var auth0 = new ManagementClient({...});

auth0.rulesConfigs.set({ key: 'dbconnectionstring' }, { value: 'secret' }).then(...)

auth0.rulesConfigs.delete({ key: 'dbconnectionstring' }).then(...)

auth0.rulesConfigs.getAll().then(...)

[Floppy]

This is great, I'd love it if this could be merged in :)

[luisrudge]

Can you fix the conflicts so I can merge? Thanks!

[stevezau]

I fixed the conflicts.. @luisrudge can we merge, need it for the deploy-cli work i'm doing.