fix broken version comparison used during ssl tests

[emmettbutler]

This pull request fixes a version comparison operation that caused ssl tests not to run under kafka 0.10.

[codecov-io]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@26ce1c0). Click here to learn what that means. The diff coverage is 0%.

@@            Coverage Diff            @@
##             master     #682   +/-   ##
=========================================
  Coverage          ?   81.25%           
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  Files             ?       25           
  Lines             ?     3302           
  Branches          ?      485           
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  Hits              ?     2683           
  Misses            ?      479           
  Partials          ?      140

Impacted Files	Coverage Δ
pykafka/connection.py	77.65% <0%> (ø)

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[emmettbutler]

See the travis runs on this branch - ssl connections are currently failing with dh key is too small.