Allow user to specify JVM options through environment variable

[tongwang]

I'd like to set heap sizes of the Tika server. However I couldn't find a way to do so. How about having an environment variable (JAVA_OPTS or TIKA_JAVA_OPTS) that users can pass JVM options to the container?

[mpdude]

Don’t know if it helps: IIRC there is a way to make Java detect it’s running in a container and use all available container memory.

That way, you can assign memory limits when starting the container.

[mpdude]

https://developers.redhat.com/blog/2017/03/14/java-inside-docker/

[arjunyel]

This should let it auto detect and adapt to the memory #20

[mpdude]

@tongwang Could you please check if this has been resolved by #20 and if so, close this issue here?