Naming consistency in SceneManager

Updated command functions to conform with the 'Handle<command>' format
Correct WebUI user counts (Issue #38)

* WebUI - online_users, grid status
  - Update html code for additional formatting and readability

* UserInfoConector
  - Correct RecentlyOnline queries to convert local times to UTC that
is used for logging avatar presence

* UserAccountService
  - Ignore system users in retrieved user count