Select2 parameter 'first_empty' should be set to false for the controls of type array.
If it is true then on deselecting/clearing all the values, an empty entry is still there.
Fixes#4751
Remove extra comma in the function argument while starting the query tool.
Other browsers had no problems, but it is an issue on Internet explorer.
Fixes#4769
Werkzeug middleware allows us to set the number of trusted ports and few other params
behind the proxy. By default values are set to zero.
Added 'X-Forwarded-*' configuration options and set the default value of the port to 1 to work with non-standard port.
Fixes#4768
