Support setting parent_controller

[jaynetics]

fixes #618

for the interface, i mirrored Devise::parent_controller=.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.92%. Comparing base (43645af) to head (f604919).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #903   +/-   ##
=======================================
  Coverage   98.92%   98.92%           
=======================================
  Files          14       14           
  Lines         557      558    +1     
=======================================
+ Hits          551      552    +1     
  Misses          6        6           

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[jaynetics]

rebased to bring up-to-date with master.

@tagliala could we get this one merged?

[tagliala]

I think this may be an interesting change, I may need this for a use case where I want to alias current_admin_user to current_user and add some other admin-specific actions

[jaynetics]

My use case is the same as in the original issue: running rails in API mode.

I've been using this fork and the setting parent_controller = 'ActionController::Base' in production for 8 months now without issues.

[javierjulio]

Thanks!