Bug 574907 - Move BREE to 1.8, Eclipse to 4.8 in Target, and Tycho to
2.3 in order to support building against Eclipse 4.20

Change-Id: I95876c390dce809e25797526abdca144e08753eb
Signed-off-by: Johannes Faltermeier <jfaltermeier@eclipsesource.com>