force-migration config for remove-brick operation.

The cli will take input from the user before starting "remove-brick"
start operation. The message/confirmation looks like the following:

<Running remove-brick with cluster.force-migration enabled can result
in data corruption. It is safer to disable this option so that files
that receive writes during migration are not migrated. Files that are
not migrated can then be manually copied after the remove-brick commit
operation. Do you want to continue with your current
cluster.force-migration settings? (y/n)>

And also question for COMMIT_FORCE is changed.

Fixes: bz#1572586
Change-Id: Ifdb6b108a646f50339dd196d6e65962864635139
Signed-off-by: Susant Palai <spalai@redhat.com>

There are around 300 regression tests, 250 being in tests/bugs. Running
partial set of tests/bugs is not easy because this is a flat directory
with almost all tests inside.

It would be valuable to make partial test/bugs easier, and allow the use
of mulitple build hosts for a single commit, each running a subset of
the tests for a quicker result.

Additional changes made:
- correct the include path for *.rc shell libraries and *.py utils
- make the testcases pass checkpatch
- arequal-checksum in afr/self-heal.t was never executed, now it is
- include.rc now complains loudly if it fails to find env.rc

Change-Id: I26ffd067e9853d3be1fd63b2f37d8aa0fd1b4fea
BUG: 1178685
Reported-by: Emmanuel Dreyfus <manu@netbsd.org>
Reported-by: Atin Mukherjee <amukherj@redhat.com>
URL: http://www.gluster.org/pipermail/gluster-devel/2014-December/043414.html
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/9353
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Reviewed-by: Emmanuel Dreyfus <manu@netbsd.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>