object-storage: use tox for unit tests; fix em too

Add the ability to use tox for unit tests, since it helps us solve the
problem of supporting multiple branches that require different
versions of dependencies, and allows us to possibly support multiple
versions of python in the future.

Also fix the code to work with pre-grizzly environments, by not
requiring the constraints backport.

Also fixed the xattr support to work with both pyxattr and xattr
modules.

And fixed the ring tests to also work without a live /etc/swift
directory.

BUG: 948657 (https://bugzilla.redhat.com/show_bug.cgi?id=948657)
Change-Id: I2be79c8ef8916bb6552ef957094f9186a963a068
Signed-off-by: Peter Portante <peter.portante@redhat.com>
Reviewed-on: http://review.gluster.org/4781
Reviewed-by: Alex Wheeler <wheelear@gmail.com>
Tested-by: Alex Wheeler <wheelear@gmail.com>
Reviewed-by: Anand Avati <avati@redhat.com>
storage/posix: introduce node-uuid-pathinfo

enabling this option has an effect on pathinfo xattr
request returning <node-uuid>:<path> instead of the
default - which is <hostname>:<path>.

Change-Id: Ice1b38abf8e5df1568bab6d79ec0d53dfa520332
BUG: 765380
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/4567
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>
object-storage: rebase Swift to 1.8.0 (grizzly)

Change-Id: I24265c12a45eac4cec761748096118c9647440be
BUG: 948039
Signed-off-by: Kaleb S. KEITHLEY <kkeithle@redhat.com>
Reviewed-on: http://review.gluster.org/4779
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>
afr: let eager-locking do its own overlap checks

Today there is a non-obvious dependence of eager-locking on
write-behind. The reason is that eager-locking works as long
as the inheriting transaction has no overlaps with any of the
transactions already in progress. While write-behind provides
non-overlapping writes as a side-effect most of times (and only
guarantees it when strict-write-ordering option is enabled,
which is not on by default) eager-lock needs the behavior
as a guarantee. This is leading to complex and unwanted checks
for the presence of write-behind in the graph, for the simple
task of checking for overlaps.

This patch removes the interdependence between eager-locking
and write-behind by making eager-locking do its own overlap checks
with in-progress writes.

Change-Id: Iccba1185aeb5f1e7f060089c895a62840787133f
BUG: 912581
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/4782
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>