Fixes to work using a reverse proxy

[alnviana]

When using a reverse proxy with Subpath, the notifications don't load. The call is made to http://host/api/user_notifications.json instead of http://host/netalertx/api/user_notifications.json.
When I compared it to the table_devices.json request (which works), I realized that it probably works there because it's relative. When I changed it manually on the server to test, the notifications appeared.

I don't think changing this should cause any problems, as table_devices.json already works like this. However, as everything in IT is strange, any small change can cause unexpected errors, so I suggest you test it too. :)

Not working:

Working:

Edit:
I saw some other requests that were giving the same problem, so I decided to look up everything that used '/api' and found these two more.

table_appevents.json

table_notifications.json

[jokob-sk]

@alnviana thanks a lot!