Migrations and cleanup

[FinalAngel]

Added missing migrations from picture and link updates

pinned versions to match link and picture releases

[codecov-io]

Codecov Report

Merging #93 into master will increase coverage by 0.43%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #93      +/-   ##
==========================================
+ Coverage   67.23%   67.66%   +0.43%     
==========================================
  Files          66       69       +3     
  Lines        1346     1364      +18     
  Branches       96       96              
==========================================
+ Hits          905      923      +18     
  Misses        433      433              
  Partials        8        8

Impacted Files	Coverage Δ
...tstrap4_link/migrations/0004_auto_20190703_0831.py	100% <100%> (ø)
...rap4_picture/migrations/0004_auto_20190703_0831.py	100% <100%> (ø)
...ap4_carousel/migrations/0004_auto_20190703_0831.py	100% <100%> (ø)

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