Bug 538461 : let MavenBuilder use a null scheduling rule

Added an experimental and semi-hidden  preference to make
the Maven builders scheduling rule null.
The preference will be visible when Eclipse is started with
the -Dm2e.showExperimentalFeatures=true flag (in eclipse.ini)

Change-Id: Ieb231142368927ed9d138afa400f1ad1cec175a1
Signed-off-by: Mickael Istria <mistria@redhat.com>
8 files changed