Changed project import page checkboxtable into a filtered tree.

Changed project import page checkboxtable into a filtered tree.

With large repositories it is difficult to get a subset of projects
because the import projects tree could not be filtered. Now the
import projects uses a filtered tree which is commonly used inside
Eclipse.

- The tree can be filtered with *text like syntax.
- If a project is selected it always stays in the view even if it
  does not match the filter.
- If projects are deselected with the "deselect all" button they can
  be removed from the view if it does not match the filter string.
  This is done by calling setinput again. This is not done for
  individual deselections because that did not look right and I am
  not sure about the setinput overhead on really large repositories

I have tested this with the following repositories:
git://github.com/smilebase/org.eclipse.mylyn.github.git
git://github.com/aptana/studio.git
git://ecf1.osuosl.org/home/gitcvs
and the egit and jgit repositories

It was noticed that some of the aptana and ecf projects (notably the
feature projects) were not attached to teaming after import. This is
probably not caused by this change.

Change-Id: I6fb40104863323aaf66ea355f3574e08fa775b17
Signed-off-by: Wim Jongman <wim.jongman@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>