poc pagination
playing with angular.
* adapted old styling.
* created a loading-indicator as direcitve. thanks to
https://github.com/MandarinConLaBarba/angular-examples/blob/master/loading-indicator/index.html
* added pagination
added first services
* replaced mailService in favour of FolderResource and MailResource
* moved minig.css from assets/ to resources/css
clear currentPage to one on folder change