Implemented usage of default hierarchy file located in the root
directory of the execution path of the UI (e.g. the eclipse folder).
Later the default hierarchy will be fetched from the server instead.

Change-Id: I1147814191c599a820e47e917ca0dbe5cc1ad2cc
Signed-off-by: Denis Knoepfle <denis.knoepfle@sap.com>
Changed extensions add dialog to be similar to the add properties
dialog.

Added scrollbars to the description text in the add dialogs.

Fixed a bug when caching the extension descriptions in
ServiceClientWrapper.

Added scrollbars to the resources list.

Change-Id: I7d2d579a7c8963cbc9786b1bcac67129f40d3305
Signed-off-by: Denis Knoepfle <denis.knoepfle@sap.com>