Dockerfile with debian buster/remote branch support

[roflmao]

Inspired by #28 i created a seperate Dockerfile for building directly from a branch configurable with docker build --build-args:

$ docker build --build-arg Z2M_BRANCH=feat#startStop --build-arg ZWJS_BRANCH=master --no-cache -t zwavejs2mqtt:startStop -f docker/Dockerfile.contrib.master .

It also uses latest debian stable (buster).

[coveralls]

Pull Request Test Coverage Report for Build 393641739

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 28.785%

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Totals
Change from base Build 393291034:	0.0%
Covered Lines:	1827
Relevant Lines:	6474

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💛 - Coveralls

[roflmao]

It will build both zwavejs2mqtt/node-zwave-js from master if no build args defined.

[robertsLando]

@roflmao Seems like a duplicate of the other Dockerfile, I know it's a little different but I cannot keep both