Note 1) we're not supposed to be using #!/usr/bin/env python, see
https://fedoraproject.org/wiki/Packaging:Guidelines?rd=Packaging/Guidelines#Shebang_lines

Note 2) we're also not supposed to be using "!/usr/bin/python,
see https://fedoraproject.org/wiki/Changes/Avoid_usr_bin_python_in_RPM_Build#Quick_Opt-Out

The previous patch (https://review.gluster.org/19767) tried to do too
much in one patch, so it was abandoned.

This patch does two things:
1) minor cleanup of configure(.ac) to explicitly use python2
2) change all the shebang lines to #!/usr/bin/python2 and add them
where they were missing based on warnings emitted during rpmbuild.

In a follow-up patch python2 will eventually be changed to python3.

Before that python2-isms (e.g. print, string.join(), etc.) need to be
converted to python3. Some of those can be rewritten in version agnostic
python. E.g. print statements become print() with "from __future_ import
print_function". The python 2to3 utility will be used for some of those.
Also Aravinda has given guidance in the comments to the first patch for
changes.

updates: #411
Change-Id: I471730962b2526022115a1fc33629fb078b74338
Signed-off-by: Kaleb S. KEITHLEY <kkeithle@redhat.com>

- gsyncd gets allow-network tunable which is expected to
  hold a comma-separated list of IP network addresses
- for IP addess matching, bring in ipaddr module from Google
  (http://code.google.com/p/ipaddr-py/, rev. trunk@225)

This will let users control master's access to slave's volumes
until we implement unprivileged geo-rep (delayed due to some
technical issues). It's also needed for the completeness of
our hardening efforts, as plain file slaves won't be able
to work with an unprivileged gsyncd.

Change-Id: I58431cba6592f8672e93ea89a5eef478905b00b9
BUG: 2825
Reviewed-on: http://review.gluster.com/488
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vijay@gluster.com>