Reenable the ability to turn off trace messages during junit run

Fixes https://github.com/bndtools/bnd/issues/622

Signed-off-by: BJ Hargrave <bj@bjhargrave.com>
Merge pull request #623 from bjhargrave/issue622

Reenable the ability to turn off trace messages during junit run
Update CONTRIBUTING documentation

Remove provisional statement as this process is fully in effect.

[ci skip]

Signed-off-by: BJ Hargrave <bj@bjhargrave.com>
Merge pull request #624 from bjhargrave/contributing

Update CONTRIBUTING documentation