MB-26600: Remove python 2.6 non-compliant APIs
MB-26600: Remove python 2.6 non-compliant APIs

cbcollect_info uses with a as ip, b as op to open files.
This is supported only in 2.7. Since the server still ships with
python 2.6 revert this to nested file managers.

Change-Id: I3c770faf66c3c955ee0ebacd32f37bca493275a2
Reviewed-on: http://review.couchbase.org/88550
Tested-by: Amit Krishnan <2d9be4f8a4cc2611c6b78293f950d6eb7edc7196@gmail.com>
Well-Formed: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server