freezer-agent python2 and 3 freebsd

[Jesper Schmitz Mouridsen]

I have been doing some light testing of freezer-agent on FreeBSD 11.1 with python 3.5
This is a patch to master 32950bf4c5d012e4da963d4587be8258604c4eaf
eventlet must be updated to 0.22.1 in order to avoid AttributeError: module 'eventlet.green._socket_nodns' has no attribute 'EAI_NODATA'

Only testing backup and restore to/from remote ssh ( no swift or keystone involved)
The issues are:

-iteritems in Dict does not exist in python3 (Solution (at least for python3) use items))
-Different path of bash (Solution rely on OS PATH ENVIRONMENT e.g specify simply bash)
(bash is not installed by default on FreeBSD but is a pkg)
-Default gtar file path on FreeBSD is /dev/sa0 (Solution specify -f - for stdout)
-queues.SimpleQueue init was missing context ctx parameter in init, solution is to ensure to import from multiprocessing.
-Two places str are encoded to bytes with encode in order to write to a file in binary mode, and in order to compare correctly.

Patch attached.

[Jesper Schmitz Mouridsen (jsmdk)]

For python2.7 only the tar and bash problem exists.
and eentlet must still be updated, in order to avoid 'eventlet.green._socket_nodns' has no attribute 'EAI_NODATA'