Prevent init new peer connection, in case of it already established

[mustafaboleken]

ant-media/conference-call-application#193

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 55.44%. Comparing base (37317aa) to head (89c76da).
Report is 17 commits behind head on master.

❗ Current head 89c76da differs from pull request most recent head 0df14f4

Please upload reports for the commit 0df14f4 to get more accurate results.

Files	Patch %	Lines
src/main/js/webrtc_adaptor.js	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #440      +/-   ##
==========================================
- Coverage   55.98%   55.44%   -0.54%     
==========================================
  Files           7        5       -2     
  Lines        1513     1358     -155     
==========================================
- Hits          847      753      -94     
+ Misses        666      605      -61     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.