Adapted registry interface to newest API version

[johannesduesing]

Reason for this PR
This PR changes the Delphi registry HTTP interface in order to be more REST-like (as discussed here). The status report endpoints that each of the Delphi components calls have to be adapted to the new API specification.

Changes in this PR

• Adapted URLs that are being called to the new API schema
• Removed unused code in InstanceRegistry.scala

[bhermann]

Looks good to me

[codecov-io]

Codecov Report

Merging #42 into develop will increase coverage by 0.1%.
The diff coverage is 0%.

@@           Coverage Diff            @@
##           develop    #42     +/-   ##
========================================
+ Coverage     1.39%   1.5%   +0.1%     
========================================
  Files           19     19             
  Lines          429    399     -30     
  Branches        33     24      -9     
========================================
  Hits             6      6             
+ Misses         423    393     -30

Impacted Files	Coverage Δ
...t/delphi/instancemanagement/InstanceRegistry.scala	0% <0%> (ø)	⬆️

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[johannesduesing]

I fixed the issue codacy was complaining about (a variable name starting with an uppercase character). This PR should be ready to merge now