Problems pane, color output, docker and custom command

• BREAKING CHANGE Updated vscode engine version required to latest 1.27.0.
• Add color output and show failed tests in problems pane by running a task using a problem matcher.
• Add config property phpunit.docker.image for choosing docker image for DockerDriver.
• Add DockerContainerDriver to find running containers and pick from list.
• Add phpunit.docker.container to set running container to use for DockerContainerDriver.
• Add phpunit.command config for running custom commands in place of php. Such as custom docker commands.
• Add phpunit.paths to map paths for virtual environments. String replace with regex will be used for all paths in this config. Ex config:

{
    "/local/path": "/vitual/path",
    "/second/local/path": "/second/virtual/path"
}