Optimize che-launcher for perf

[TylerJewell]

What does this PR do?

This pull request implements optimizations to minimize the number of times that docker run is called within the che-launcher utility. Previously, there were numerous helper functions that have embedded docker run commands. If these functions were repeatedly called, we were launching unnecessary containers when one invocation will do.

Also fixes a small error where one of the docker run commands did not have a --rm leaving a lot of lingering exited containers on the user's system.

Also adds in a build.sh into the directory to perform a build of the image.

[TylerJewell]

@benoitf @l0rd @riuvshin - FYI - one of you +1. The speed of a che info command is now dramatically faster.

[codenvy-ci]

Build # 71 - FAILED

Please check console output at https://ci.codenvycorp.com/job/che-pullrequests-build/71/ to view the results.

[l0rd]

@TylerJewell 👏 👏 the launcher is really faster now.

I have one comment:

You are calling 3 times docker run at the beginning of the launcher to set ETH0_ADDRESS, ETH1_ADDRESS and DOCKER0_ADDRESS but you really just need one of them. You can check if DEFAULT_DOCKER_HOST_IP has already been set at the very beginning ofget_docker_host_ip()` instead:

if [ -n "${DEFAULT_DOCKER_HOST_IP}" ]; then
    echo "${DEFAULT_DOCKER_HOST_IP}"
fi

You could do the same in has_docker_for_windows_ip() and get_che_launcher_version(): if the variables are already set don't run the command, otherwise run it.

As a result you will be able to call the functions directly as many times as you need and you should not need to worry to run all the docker run command at the beginning (but just when you need them).

[TylerJewell]

@l0rd - so I studied this for a bit this morning and concluded that the system would not profit. In order to implement variable check within get_docker_host_ip, I'd have to reintroduce additional docker run command back into is_docker_for_windows to avoid an infinite loop, thus impacting performance again.

[TylerJewell]

Added a fix for #2102 as well.

[l0rd]

LGTM

[codenvy-ci]

Build success. https://ci.codenvycorp.com/job/che-pullrequests-build/85/