Update default session options to use Cilantro config

The default ping interval has been increased to 30 seconds
and can be set at `session.defaults.ping`. If the value is null,
pinging will be disabled.

Fix #481

Signed-off-by: Byron Ruth <b@devel.io>
Merge pull request #482 from cbmi/issue-481

Update default session options to use Cilantro config