Support a dockerized analyticstack

[mulby]

This PR is part of the dockerization of the analyticstack, most of the documentation can be found here: https://github.com/edx/configuration/pull/3582

It implements the following changes:

1. Add a docker.cfg config file that contains all of the settings needed to run in a docker-compose environment.
2. Add Makefile targets specified by OEP-5 that allow a standard interface for managing the containers.
3. Support running acceptance tests with "launch-task" instead of "remote-task". This allows us to run the acceptance tests from the container without SSH-ing into itself and re-deploying the pipeline when executing every test. Eventually this could be used to run the acceptance tests in Travis or another third-party CI system that supports docker-compose based test execution.
4. A bunch of detail in the README.md describing how to set it all up.

FYI: @HassanJaveed84

TODO:

• [x] Implement the OEP-5 standard Makefile targets
• [x] Clean up the formatting of README.md
• [ ] Implement the part of OEP-5 that specifies how containers are built

[codecov-io]

Current coverage is 73.79% (diff: 100%)

Merging #337 into master will decrease coverage by 5.94%

@@             master       #337   diff @@
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  Files           191         92     -99   
  Lines         19676      10236   -9440   
  Methods           0          0           
  Messages          0          0           
  Branches          0          0           
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- Hits          15691       7554   -8137   
+ Misses         3985       2682   -1303   
  Partials          0          0           

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[tobz]

I'm sure you've seen this, but it looks like we need to open up those luigid images, or add them if they're actually just missing.

[mulby]

@tobz yeah none of the images have been pushed up to docker hub yet... so the docker-compose stuff won't yet work in Travis. I was mostly just sketching out how it could work.

[tobz]

A ha! Gotcha. :)