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
Add ejabberd_node_utils:file_exists/2 that takes a nodes into account

Previously this function was checking file existence based on the node
name from the CT ejabberd_node config value.
Change certificate file location to /tmp/server.pem

The server.pem file is copied to /tmp while running devrel Make target.