* feat(emqx_conf): move conf manager for emqx_machine to emqx_conf
* chore(emqx_conf): change emqx:get_config/2 to emqx_conf:get/2
* fix: common test failed
* fix: badmatch by typo wrong key
* fix(emqx_conf): get the wrong core nodes
* fix(emqx_conf): get core node's tnx_id not latest tnx_id
* fix: add ro_transation when copy conf file
* fix: delete debug info
* fix: change ekka_rlog to mria_rlog
* fix: remove cluster_rpc from emqx_machine.
* fix: don't call ekka:start/0 explicitly
* fix: ekka should be start in emqx_machine
* feat(gateway): add gateway application
* chore(gateway): add normalize confs function
* refactor: move emqx-stomp to emqx-gateway subdir
* chore(gateway): fix some bad function defination
* chore(gateway): rename type to gwid
* chore(gw-stomp): upgrade the implementation to suppport gateway instance
* feat(gw-stomp): add reconnect mechanism
* refactor(stomp): upgrade connection&channel module to latest
* refactor(stomp): more details for handle_in/out
* refactor(stomp): get it up and running
* chore(gw): load some modules by default
* refactor: upgrade the emqx-gateway schema module
* test(stomp): fix testcases for stomp gateway
* chore(gw): remove needless lines
* chore(gateway): correct a lot of specs
* chore(gw): add a draft for metrics
* chore(gw): add metrics process
* fix(gw): fix cm process monitor
* test(gw): add test cases for gateway-regitry
* feat(gw): add metrics/cli for gateway
* fix(gw): fix xref errors
* chore(gw): pretty gateway metrics print format
* chore(gw-stomp): generate clientid by default
* chore(gw): more reliable
* chore(gw): rename gwid -> type
* chore(gw): impl the update logic
* chore(gw): some format improvement
* chore(gw): adapts the hocon configs
* fix(gw): fix xref errors
* test(gw): update configurations for tests
* chore(gw): ignore diaylzer warnings
* fix(gw): fix bad function call
* chore(gw): remove needless comments