Enable $LOTSOFDEVICES (#325)

From https://hub.docker.com/r/jacobalberty/unifi:

> Enable this with `true` if you run a system with a lot of devices and/or with a low powered system (like a Raspberry Pi). This makes a few adjustments to try and improve performance:
>
> - enable `unifi.G1GC.enabled`
> - set `unifi.xms` to `JVM_INIT_HEAP_SIZE`
> - set `unifi.xmx` to `JVM_MAX_HEAP_SIZE`
> - enable `unifi.db.nojournal`
> - set `unifi.dg.extraargs` to `--quiet`

See also https://help.ui.com/hc/en-us/articles/115005159588-UniFi-How-to-Tune-the-Network-Application-for-High-Number-of-UniFi-Devices.

docker-compose.yaml

@@ -6,6 +6,9 @@ services:
     restart: "always"
     user: "unifi"
     environment:
+      JVM_INIT_HEAP_SIZE: "2g"
+      JVM_MAX_HEAP_SIZE: "2g"
+      LOTSOFDEVICES: "true"
       UNIFI_STDOUT: "true"
     ports:
       - "${UNIFI_HTTP_PORT:-8080}:8080/tcp"