feat: Adding check-in endpoints

[stoopidJSON]

This will add check-in models. The endpoints will actually come in another
Commit. This commit also cleans up some foreign key lookups for other tables.
resolves #6

Todos

• Models
• [ ] Seeders
• [ ] Endpoints
• Add checkIn option to Entity
• Tests

[codecov]

Codecov Report

Merging #60 into master will decrease coverage by 6.03%.
The diff coverage is 31.70%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
- Coverage   85.39%   79.36%   -6.04%     
==========================================
  Files          12       12              
  Lines         226      252      +26     
==========================================
+ Hits          193      200       +7     
- Misses         33       52      +19     

Impacted Files	Coverage Δ
src/models/user.js	89.28% <0.00%> (ø)
src/routes/user-role.js	90.47% <ø> (ø)
src/routes/entity.js	47.61% <21.73%> (-21.62%)	⬇️
src/routes/contact.js	62.96% <28.57%> (-2.43%)	⬇️
src/routes/user.js	89.28% <50.00%> (-3.31%)	⬇️
src/models/entity.js	71.42% <60.00%> (-6.35%)	⬇️
src/models/contact.js	78.57% <66.66%> (-3.25%)	⬇️

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