Running container requires the use of env variables

[krumware]

This issue is for tracking and explanation:
Currently, running this container requires the use of env variables. This is due to the need to bypass launching the IB Gateway using the original internal script /IBController/IBControllerGatewayStart.sh.
If we didn't bypass this script, our environmental variables would be overwritten by the defaults, so we must bypass this script in order to be able to use the env vars.

In future releases of the IB Gateway, either through QuantConnect's fork or otherwise, the original maintainers of IB Gateway may choose to add env var support to this script, but (opinion incoming) that is outside the responsibility of this repo.

[krumware]

We may be able to re-enable default vars by adding an IF check in runscript.sh to check for the existence of ENV vars. If they are missing, run the original /IBController/IBControllerGatewayStart.sh script.

[krumware]

Tagged as help wanted in case anyone wants to take a stab at this