Tours API

This pull request contains 3 separate commits:
1. For the new Tours Authoring API
    Tracked by code review http://mrccodereview.cloudapp.net/ui#review:id=1213

2. Introducing maxlength and nvarchar for all strings in the Entity classes

3. Introducting a storage timeout value.

2 & 3 are tracked by code review http://mrccodereview.cloudapp.net/ui#review:id=1224 and bug https://github.com/alterm4nn/ChronoZoom/issues/464