Re-emit for a given database using event emitters.

Provides a cleaner solution than building separate
functions (which can then not be removed).

Addresses nEDM-TUM/nEDM-Interface#14
Making DatabaseStatus an object, which ensures
that the button updates (for databases) are always called.

Closes nEDM-TUM/nEDM-Interface#14
Allow turning on/off display of DB write status.

Now shows up in a toastr div, floating in bottom left.

Closes nEDM-TUM/nEDM-Interface#17
Bug fixes in MonitoringGraph.