check if given session is alive
use escalus from branch bosh-suite-stability-improvements
wait for server to close a session
Merge pull request #91 from esl/bosh-suite-stability-improvements

BOSH suite stability improvements
use specific commit from escalus

85cbe4b48e18f77a5383a8e45712eddd958ae32f
Test HTTP API with katt
Test OPTIONS call to metrics service
Test initial users API service
Skip users_api_SUITE for external authentication