Merge pull request #20 from Sbfrr/spec_provider

Spec provider
Presence validation of association added to Customer and Provider models
Merge pull request #21 from Sbfrr/validation

Presence validation of association added to Customer and Provider models
Make unrelated specs pending
Figaro gem added to gemfile in order to store Pusher api key
Scope :available and :busy added to Provider model
provider index added
ProvidersController ready to be tested
Merge pull request #22 from Sbfrr/UbContr

Uberify  ProvidersController ready to be tested
Solve conflicts