handle java memory and options better in container

Four requirements:

a. Grouper should be able to have defaults for CATALINA_OPTS and max memory

b. It should be possible to set the memory tomee uses without affecting the other Grouper defaults

c. It should be possible to add additional CATALINA_OPTS without affecting the Grouper defaults

d. It should be possible to override all the grouper CATALINA_OPTS

So this is for the 2.5.21 container (which is not ready yet, but when it is...) 

I think we need an env variable for max memory, e.g.

GROUPER_MAX_MEMORY=4g

In the container, it should:

1. if that is not set, set it to 1500m   (default)
2. If there is no CATALINA_OPTS set, then set

CATALINA_OPTS="-Xmx$GROUPER_MAX_MEMORY -XX:+UseG1GC -XX:+UseStringDeduplication $GROUPER_EXTRA_CATALINA_OPTS"

So, to just set the memory if you dont want 1.5g: you just pass

 -e GROUPER_MAX_MEMORY='6g'

To set other catalina opts and keep Grouper's defaults, just set

 -e GROUPER_EXTRA_CATALINA_OPTS='-XX:whatever'

If you want to override Grouper's default, set

 -e CATALINA_OPTS='-XX:something -XX:somethingelse'