* Move the oled script's PiCmds module to common, and rename it SysCmds.
* Use sys_cmds.get_ip_and_host() in web UI code.
* Move the auth_active() method to device_utils
* Rename device_utils to web_utils. Make auth_active() method take the group as argument.
* Migrate all pi_cmds methods to the SysCmds common class.
* Display hostname and ip in Web UI.
* Resolve or suppress pylint warnings.
* Resolve a pylint warning.
* Resolve or suppress pylint warnings.
* Import libraries at the top level for readability. In my testing on a Pi3B+, this leads to ~1.5k more memory being used by the python3 process.
* Change page title as requested by akuker.
* Reenable the import-outside-toplevel pylint rule.
* Resolve pylint warnings.
* Fix error following refactoring.
* Minor UI tweaks.
* Cleanup.
* Break out bridge config validation into a utility method.
* Move the dropzonejs method into the web_utils package
* Move get_logs method into SysCmds class.
* Improve get logs UI.
* Resolve pylint warning.
* Standardize class instance name.
