Update usage of IAdaptable#getAdapter

Update usage of IAdaptable#getAdapter

Generics were added to the APIs of IAdaptable and related
classes. Update our usage of these methods, as suggested in
http://dev.eclipse.org/mhonarc/lists/cross-project-issues-dev/msg11590.html

Change-Id: I8fb374869567b5c2b7421b4773998c60e9fcc468
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/43472
Reviewed-by: Hudson CI
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>