Add Python 3.6 to test matrix

[Roman3349]

Signed-off-by: Roman3349 ondracek.roman@centrum.cz

[coveralls]

Coverage increased (+1.4%) to 38.595% when pulling 0212521 on Roman3349:travis-ci/python3.6 into 004d8be on gammu:master.

[codecov-io]

Codecov Report

Merging #13 into master will increase coverage by 1.38%.

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
+ Coverage   36.31%   37.69%   +1.38%     
==========================================
  Files          46       46              
  Lines        1666     1666              
  Branches      204      203       -1     
==========================================
+ Hits          605      628      +23     
+ Misses       1046     1023      -23     
  Partials       15       15

Impacted Files	Coverage Δ
test/test_dummy.py	98.49% <ø> (+6.53%)	✅
test/test_worker.py	97.77% <ø> (+22.22%)	✅

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[coveralls]

Coverage increased (+1.4%) to 38.595% when pulling 0212521 on Roman3349:travis-ci/python3.6 into 004d8be on gammu:master.

[coveralls]

Coverage increased (+1.4%) to 38.595% when pulling 0212521 on Roman3349:travis-ci/python3.6 into 004d8be on gammu:master.

[coveralls]

Coverage increased (+1.4%) to 38.595% when pulling 0212521 on Roman3349:travis-ci/python3.6 into 004d8be on gammu:master.

[coveralls]

Coverage increased (+1.4%) to 38.595% when pulling 0212521 on Roman3349:travis-ci/python3.6 into 004d8be on gammu:master.

[coveralls]

Coverage increased (+1.4%) to 38.595% when pulling 0212521 on Roman3349:travis-ci/python3.6 into 004d8be on gammu:master.

[nijel]

Obviously @coveralls went crazy on commenting this. Thanks for PR, merging.