Make it possible to run from Enviroments that do not directly have Pycall

[oxinabox]

This adds a Project.toml
so that we can run the workers in the TensorFlow enviroment,
which will have PyCall for sure.

When making the Project.toml i did not both to transcribe the Compat rules,
since they are basically not julia 0.7 compat anyway.

[malmaud]

Cool cool. Is there a guide somewhere on how Project.toml and the whole environment-based package system works?

[oxinabox]

Pkg.jl docs.

It could be better, but I have tried and I can't make it better yet.

[malmaud]

OK, I get what this PR does now. Looks good, merge when you're ready.

[codecov]

Codecov Report

Merging #493 into master will increase coverage by 0.28%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #493      +/-   ##
==========================================
+ Coverage   49.04%   49.32%   +0.28%     
==========================================
  Files          79       79              
  Lines        2659     2668       +9     
==========================================
+ Hits         1304     1316      +12     
+ Misses       1355     1352       -3

Impacted Files	Coverage Δ
src/TensorFlow.jl	57.89% <100%> (ø)	⬆️
src/version.jl	73.33% <0%> (+10.58%)	⬆️

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[codecov]

Codecov Report

Merging #493 into master will increase coverage by 0.28%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #493      +/-   ##
==========================================
+ Coverage   49.04%   49.32%   +0.28%     
==========================================
  Files          79       79              
  Lines        2659     2668       +9     
==========================================
+ Hits         1304     1316      +12     
+ Misses       1355     1352       -3

Impacted Files	Coverage Δ
src/TensorFlow.jl	57.89% <100%> (ø)	⬆️
src/version.jl	73.33% <0%> (+10.58%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5b8ff66...434a778. Read the comment docs.