If an empty username or password are given during the initialization
of `emqx_dashboard_admin`, it'll return just the atom `ok`, which
breaks the expected `{ok, _}` in `emqx_dashboard_app:start/2`.
```
{'EXIT',
{{failed_to_start_app,emqx_dashboard,
{emqx_dashboard,
{bad_return,
{{emqx_dashboard_app,start,[normal,[]]},
{'EXIT',
{{badmatch,ok},
[{emqx_dashboard_app,start,2,
[{file,
"/home/thales/dev/emqx/emqx/apps/emqx_dashboard/src/emqx_dashboard_app.erl"},
{line,32}]},
{application_master,start_it_old,4,
[{file,"application_master.erl"},{line,293}]}]}}}}}}}}
```
* fix(dashboard_api): delete non-exist user wrongly return 204
* fix(dashboard): dashboard user should use `tags` not `tag`
* fix(dashboard): create/update user return 200 with full users list
* fix(dashboard): logout status code 204
* fix(dashboard): update pwd status code 204
* test: test suite for dashboard APIs
* refactor(dashboard): user info mnesia record name use description
* style: make elvis happy
* fix(api): dashboard swagger check request should not override env
* fix(dashboard): add/modify dashboard returns single record
* ci: update emqx-fvt version to new tag 1.0.2-dev1
* refactor(dashboard): rename 'password' field to 'pwdhash'
rename as it is not plaintext password stored in db
* refactor(emqx_dashboard): rename records
* test(emqx_dashboard_token): add test case to cover match specs
* feat: rewrite http api with hocon
* fix: crash when default_username is empty
* chore: udpate rewrite api with emqx_conf's cluster_rpc
* fix: spec wrong
* 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
One step closer for better code abstraction for opensorce vs enterprise
So far this relocation is to make opensource to enterprise merges
conflict free.
Zaiming (Stone) Shi