Add exclude_internal_topics option and fixed pattern subscription

[tvoinarovskyi]

Fixes #74

[tvoinarovskyi]

Should also resolve #46 issue in case of group_id is not None.

[codecov-io]

Codecov Report

Merging #111 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #111      +/-   ##
==========================================
+ Coverage   96.53%   96.55%   +0.01%     
==========================================
  Files          10       10              
  Lines        1761     1771      +10     
==========================================
+ Hits         1700     1710      +10     
  Misses         61       61

Impacted Files	Coverage Δ
aiokafka/group_coordinator.py	94.26% <100%> (+0.01%)	✅
aiokafka/client.py	98.21% <100%> (+0.04%)	✅
aiokafka/consumer.py	98.52% <100%> (+0.02%)	✅

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