improve interoperability with EJD
change the order of params in is_iq_result/2
Update intro.md
Remove invalid `protocol` option from SSLOpts passed to ssl:connect/2

Thanks to Brett Holton for pointing this out in issue #9.
Tested with R16B01 and R15B03.
Add Stream Management 1.3 namespace
Add some Stream Management stanza and predicate
Extend escalus_session with stream management support
Return features from escalus_connection:start/1,2

Bump the version accordingly (API change)!

This allows for inspecting  features returned by a server
when initiating a connection.
Add SM related is_ack and sm_request
Export is_ack/2
Export sm_request/0
Add is_failed/1 and has_ns/2 predicates
Add is_ack/1 predicate

This variant doesn't validate the number of handled stanzas.
Make SM an optional step when initiating the connection
Add ack stream element
Add is_ack_request predicate
Add is_enabled/2 predicate

This variant checks for the `resume` attribute being true.
Add stream_resumption support to escalus_session
Add enable_sm/1 stream element

This variant allows for setting `resume` attribute to enable Stream
Resumption.
Return stream management ID when enabling resumption