basic collection functionality implemented.

Squashed commit of the following:

commit f8310e78633578987bc75b537e388c3fdbcd350f
Author: Marcel Steffen <marcel.steffen@cologne-systems.de>
Date:   Wed Mar 20 15:42:02 2013 +0100

    enable createCollection and navigation between collections

commit 7a62c3236e4ce7616a3126ae25d22324738d7526
Author: Marcel Steffen <marcel.steffen@cologne-systems.de>
Date:   Fri Mar 15 23:59:47 2013 +0100

    add ImageResizer
    refactoring

commit 3b364fbd4b7d18a6aafc1ba8482a0ec5e7db9039
Author: Marcel Steffen <marcel.steffen@cologne-systems.de>
Date:   Fri Mar 15 11:24:41 2013 +0100

    refactoring

commit f3d4a52610c32de5a02b5a85d90237ec1c11c305
Author: Marcel Steffen <marcel.steffen@cologne-systems.de>
Date:   Thu Mar 14 16:16:32 2013 +0100

    implement basic ImageCollection container

commit 378872447f30c577175f302b6cff1cc911138145
Author: Marcel Steffen <marcel.steffen@cologne-systems.de>
Date:   Wed Mar 13 15:50:34 2013 +0100

    basic upload functionality
restructure application to use a Navigator