Fix unable to backup namespaced resources

[cheungpat]

The kube-resources-autosave script is unable to find the list of namespaces
and so it tries to backup resources from null namespace.

Log from kube-resources-autosave-dumper:

(...snip...)
++ jq -r .metadata.name
+ for ns in '$(jq -r '\''.metadata.name'\'' < ${DUMP_DIR}/namespaces.json)'
+ echo 'Searching in namespace: null'
+ mkdir -p /kube-resources-autosave/tmp/2017-05-09_15-18-57/null
Searching in namespace: null
(...snip...)

[jollinshead]

@cheungpat Nice find 👍 LGTM

[codecov-io]

Codecov Report

Merging #632 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #632   +/-   ##
=======================================
  Coverage   38.26%   38.26%           
=======================================
  Files          51       51           
  Lines        3316     3316           
=======================================
  Hits         1269     1269           
  Misses       1845     1845           
  Partials      202      202

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[mumoshu]

Good catch 👍 Thanks for the fix @cheungpat!