Using sessionStorage to save whether user is guest or not.

Also removes device change listener, cause when PC wakeups devices will be reconnected and we can try open the local video again.

Adds some safety checks for disabled contactlist.

It looks weird when the page reload overlay appears and the conference
continues in the background (the connection to the JVB remains active).
The library will not recover and the conference can not continue without
the signalling, so the room should be left and media stopped.

Removing translateString forces using data-i18n attributes, to make sure we do not forget to set them. Missing data-i18n attributes is a problem with late loading where we can end up without translation, without text. Missing data-i18n attributes is also problem that strings will not be translated when changing language.
Fixes a bug in invite dialog, where remove password button was shown for non moderators.

Will disconnect on ConferenceErrors.VIDEOBRIDGE_NOT_AVAILABLE.
Show the same message when either JVB is not available or Jicofo
disconnects.

We pass key which is enough to obtain the title.

Uses some ES6 syntax. Also removes inputHeight key for resolution as it makes no sence to have dictionary with one key. Removes some code duplication. Makes code consistent: method params for updateLocalStats and updateRemoteStats.