Fix load_study

[pedroripper]

Currently, when reading the psrclasses.json file from a previous study, PSRI does not check if the attributes inside the elements follow the PMD.

Also, PSRI is adding the data to the study exactly as it was in the JSON file. So when parsing an attribute that should be a Dates.Date in psrclasses.json, it reads as a string. Example:

{
  "Teta": [
      0.0
  ],
  "code": 0,
  "AVId": "string",
  "name": "string",
  "reference_id": 4,
  "Ordem": [
      0
  ],
  "Vazao": [
      0.0
  ],
  "Data": [
      "1900-01-01" <-------------
  ]
},

The new version for the load_study function has 1 new parameter:

• rectify_json_data flag. false by default

This PR fixes all these issues. It should be merged after PR #180

[codecov]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (df00f37) 79.97% compared to head (e113f9c) 79.97%.
Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #182   +/-   ##
=======================================
  Coverage   79.97%   79.97%           
=======================================
  Files          21       21           
  Lines        2847     2872   +25     
=======================================
+ Hits         2277     2297   +20     
- Misses        570      575    +5     

Files	Coverage Δ
src/OpenStudy/study_openinterface.jl	77.75% <100.00%> (+0.11%)	⬆️
src/modification_api.jl	78.17% <100.00%> (+0.45%)	⬆️
src/OpenStudy/relations.jl	80.75% <57.14%> (-0.71%)	⬇️

... and 1 file with indirect coverage changes

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