* fix(rule): reformat some code for rule-engine
* fix(lwm2m): change publish_update_when to publish_update_msg_when
Change the option name publish_update_when -> publish_update_msg_when.
Also change the object_list_changed to contains_object_list, as the
the later describes the default behavior correctly.
* fix(lwm2m): publish_update_msg_when -> update_msg_publish_condition
And move emqx app back to root level
After realising the challenges of developing plugins in standalone
rebar projects. it is perhaps more smooth to keep using emqx as
a rebar dependency
JimMoen