Common connection class

[daurnimator]

No description provided.

[coveralls]

Coverage increased (+0.4%) to 86.42% when pulling 605b8c1 on common-connection into f862d4c on master.

[coveralls]

Coverage increased (+0.4%) to 86.414% when pulling 2919ed7 on common-connection into f862d4c on master.

[daurnimator]

Beware that ssl cipher check in h2_connection might be bypassed.

[coveralls]

Coverage decreased (-0.002%) to 88.035% when pulling 4c3de1a on common-connection into 95b6ec8 on master.