Add model classes Taxonomy, Classification and Assignment
Add taxonomies to client and convert existing ones to new model
First editing views of taxonomy: definition and pie chart
Add tree map view to any taxonomy
Enable editing of taxonomy classifications (name, weights)
Enable drag and drop to order classifications
Manually edit assignments
Add #canModify to CellEditorFactory to give views more control
Add 'unassigned' category icon
Add 'unassigned' category to taxonomy definition editor
Add editing support for taxonomies in security master details page
Merge branch 'master' into feature_taxonomies
Asset allocation view using taxonomy
Cell editor factory to provide old value to modification listener
Introduce common interface: InvestmentVehicle
Improve taxonomy definition editor

* Show errors when assignment weights do not add up
* Fix assignment weighs when moving / editing weights
* mark Client dirty if taxonomy is edited
Helper classes to write more readable tests
Use taxonomies in statement of assets view / group by taxonomy
Use builder classes to simply index tests as well
Use Maven repository hosted on GitHub for remaining dependencies

In order to simplify the setup, use a custom Maven repository hosted on
GitHub for dependencies not available in other public repositories.
Right now, it concerns three artifacts: SWTChart, TreeMapLib Core and
TreeMapLib SWT.