Merge pull request amphp#105 from dickson-michael/master

Add support to Protocol::AuthSwitchResponse

Fix code style

Fix ignored port in getConnectionString() (amphp#93)

Interpret a filesystem path host as an unix domain socket

Add test for INSERT … SELECT

Test for amphp#89.

Fix ConnectionConfig key map

The key map was not being used prior.

Update example

Update to tagged amphp/sql and amphp/sql-common

Do not set $this->promise on connection creation

Ignore connection push if pool closed