Do not include log4j implementation in jgit

Do not include log4j implementation in jgit

As discussed in the bug, jgit should not include a logging
implementation, and instead rely on the product containing jgit to
configure the logging.

We have recently run into the situation, that installing egit in a (non
eclipse.org) RCP application breaks all the logging due to incompatible
logging implementations. Removal of the jgit logging implementation
should fix this.

Following further changes have been done for jgit command line:
* added log4j.properties to binary build of jgit.pgm. That file existed
in the git repository, but was not included in the eclipse binary build.
(maybe it is in the bazel build)
* removed apache.commons.logging package import from jgit.pgm. That
import is not used, and makes the logging even more confusing.

Bug: 514326
Change-Id: I6dc7d1462f0acfca9e2b1ac87e705617179ffdda
Signed-off-by: Michael Keppler <Michael.Keppler@gmx.de>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>