UI: Loading Spinner

[benoror]

Show loading spinner for promises (while fetching data with $http request) (ex. grid, form)

Branch: iss8-loading

• https://github.com/cgross/angular-busy
• https://github.com/urish/angular-spinner
• http://stackoverflow.com/questions/15033195/showing-spinner-gif-during-http-request-in-angular
• http://stackoverflow.com/questions/17838708/implementing-loading-spinner-using-- httpinterceptor-and-angularjs-1-1-5
• http://stackoverflow.com/questions/18743656/angular-ui-grid-how-to-show-a-loader