Replace hash with hash-bang to fix bug from upgrading to Angular 1.6

The default navigation hash prefix has changed from '' to '!' in Angular 1.6:
angular/angular.js#14202

Author: EnricSala

web/src/app/app.html

@@ -12,11 +12,11 @@ <h2>Publication Library</h2>
 
     <!-- Navigation buttons-->
     <div layout="row" layout-align="center center">
-      <md-button ng-href="#/publications" ng-class="{'nav-location': main.locationMatches('/publications')}">Publications</md-button>
+      <md-button ng-href="#!/publications" ng-class="{'nav-location': main.locationMatches('/publications')}">Publications</md-button>
       <span>|</span>
-      <md-button ng-href="#/authors" ng-class="{'nav-location': main.locationMatches('/authors')}">Authors</md-button>
+      <md-button ng-href="#!/authors" ng-class="{'nav-location': main.locationMatches('/authors')}">Authors</md-button>
       <span>|</span>
-      <md-button ng-href="#/publishers" ng-class="{'nav-location': main.locationMatches('/publishers')}">Publishers</md-button>
+      <md-button ng-href="#!/publishers" ng-class="{'nav-location': main.locationMatches('/publishers')}">Publishers</md-button>
     </div>
 
     <span flex></span>