Temporarily fix deps on wsock and update wsecli version

wsecli 1.1.0 and wsock 1.1.5 are Dialyzer-OK,
but wsecli 1.1.0 doesn't yet use wsock 1.1.5 by default.
We want both fetched automatically in Dialyzer-OK versions.
Merge pull request #15 from esl/typespecs-m1

Fix typespecs - milestone 1
make escalus_bosh stop on terminate msg, even w/keepalive
provide mark_as_terminated/1 to prevent escalus cleaner from sending redundant terminates
Merge pull request #16 from esl/escalus-bosh-fix

Improve escalus_bosh's handling of session termination
Run Dialyzer on Travis
Use wsecli 1.1.1 and don't explicitly depend on wsock anymore

wsecli 1.1.1 fetches wsock 1.1.5 which is the Dialyzer-OK version.