Refactoring, build improvements, docs improvements

[HadesArchitect]

Changeset:

• clean up
• Removed grunt traces
• excluded golang dependencies from git
• updated golang dependencies
• fixed and extended build instructions
• simplified installation with docker-compose environment
• switched fake-datasource to use prebuilt docker image
• moved pkg/* to backend/ for brevity
• fixed 5 tests

How to test:

• Review the changeset
• Review the docs
• Follow the instructions to build and run the project
• Run tests

Notice

• metricFindQuery related tests are still red, it looks like a regression due to changes in datasource.ts handleTsdbResponse.
• Any offers or suggestions are heartedly welcome.

[HadesArchitect]

@alexanderzobnin As promised, here is a little refactoring and installation improvements. Hope you'll like it this way but I'm very open to any suggestions.

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