Java support

[michelvocks]

First implementation of Java support in Gaia. Fixes #42

TODO:

• Find java executable dynamically.
• Add build support.
• Write tests.
• Improve/Cleanup SDK a bit.

[codecov-io]

Codecov Report

Merging #60 into master will decrease coverage by 2.5%.
The diff coverage is 51.72%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
- Coverage   55.88%   53.38%   -2.51%     
==========================================
  Files          16       14       -2     
  Lines        1419     1242     -177     
==========================================
- Hits          793      663     -130     
+ Misses        531      507      -24     
+ Partials       95       72      -23

Impacted Files	Coverage Δ
pipeline/ticker.go	0% <0%> (ø)	⬆️
scheduler/scheduler.go	64.64% <40%> (-1.08%)	⬇️
security/ca.go	72.41% <64.7%> (-3.83%)	⬇️
handlers/handler.go	83.58% <0%> (-0.93%)	⬇️
security/vault.go
handlers/vault.go

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[michelvocks]

Almost done. 🎉 🎊

Need to fix a test which is failing because maven is missing in the integration test container.

[michelvocks]

@Skarlso I will track documentation in a separate issue (#65). Please have a look 🤗

[Skarlso]

Will do today. :)