Revert "outline two ways to invoke a custom active model validator"
Revert "outline two ways to invoke a custom active model validator"

This reverts commit d163d3bf7ebb98d90977974aed8f85b7ec678afd.

Reason: The alternate approach can be documented in the guide and
not disrupt the existing flow in the readme.

Erol/rails,kmcphillips/rails,aditya-kapoor/rails,bogdanvlviv/rails,EmmaB/rails-1,felipecvo/rails,88rabbit/newRails,travisofthenorth/rails,Erol/rails,Edouard-chin/rails,alecspopa/rails,gavingmiller/rails,rafaelfranca/omg-rails,rbhitchcock/rails,kenta-s/rails,esparta/rails,eileencodes/rails,gauravtiwari/rails,Sen-Zhang/rails,notapatch/rails,hanystudy/rails,tgxworld/rails,Stellenticket/rails,Sen-Zhang/rails,ngpestelos/rails,coreyward/rails,gauravtiwari/rails,Erol/rails,yahonda/rails,Vasfed/rails,ttanimichi/rails,kachick/rails,illacceptanything/illacceptanything,kachick/rails,schuetzm/rails,kirs/rails-1,Stellenticket/rails,marklocklear/rails,mohitnatoo/rails,EmmaB/rails-1,sealocal/rails,matrinox/rails,mtsmfm/rails,Envek/rails,pschambacher/rails,samphilipd/rails,pschambacher/rails,koic/rails,illacceptanything/illacceptanything,fabianoleittes/rails,gauravtiwari/rails,sealocal/rails,jeremy/rails,hanystudy/rails,prathamesh-sonpatki/rails,printercu/rails,amoody2108/TechForJustice,tgxworld/rails,assain/rails,kddeisz/rails,felipecvo/rails,lucasmazza/rails,travisofthenorth/rails,kaspth/rails,mtsmfm/rails,eileencodes/rails,lcreid/rails,utilum/rails,deraru/rails,maicher/rails,vipulnsward/rails,Envek/rails,joonyou/rails,gfvcastro/rails,Stellenticket/rails,BlakeWilliams/rails,baerjam/rails,riseshia/railsguides.kr,schuetzm/rails,bradleypriest/rails,betesh/rails,tjschuck/rails,matrinox/rails,kamipo/rails,mijoharas/rails,gfvcastro/rails,illacceptanything/illacceptanything,fabianoleittes/rails,kenta-s/rails,travisofthenorth/rails,yhirano55/rails,kamipo/rails,ttanimichi/rails,yalab/rails,yahonda/rails,lcreid/rails,gfvcastro/rails,repinel/rails,joonyou/rails,deraru/rails,BlakeWilliams/rails,rafaelfranca/omg-rails,amoody2108/TechForJustice,printercu/rails,coreyward/rails,sergey-alekseev/rails,travisofthenorth/rails,mechanicles/rails,Edouard-chin/rails,tjschuck/rails,yawboakye/rails,mohitnatoo/rails,kaspth/rails,jeremy/rails,joonyou/rails,brchristian/rails,mathieujobin/reduced-rails-for-travis,esparta/rails,lcreid/rails,joonyou/rails,illacceptanything/illacceptanything,tjschuck/rails,elfassy/rails,palkan/rails,kmcphillips/rails,tijwelch/rails,maicher/rails,Envek/rails,tijwelch/rails,mijoharas/rails,baerjam/rails,rossta/rails,kaspth/rails,vipulnsward/rails,assain/rails,Vasfed/rails,illacceptanything/illacceptanything,yasslab/railsguides.jp,mechanicles/rails,amoody2108/TechForJustice,betesh/rails,BlakeWilliams/rails,aditya-kapoor/rails,illacceptanything/illacceptanything,rails/rails,88rabbit/newRails,mechanicles/rails,flanger001/rails,alecspopa/rails,ledestin/rails,prathamesh-sonpatki/rails,lcreid/rails,Vasfed/rails,maicher/rails,kenta-s/rails,prathamesh-sonpatki/rails,assain/rails,bolek/rails,utilum/rails,MSP-Greg/rails,brchristian/rails,samphilipd/rails,kmcphillips/rails,pvalena/rails,notapatch/rails,odedniv/rails,illacceptanything/illacceptanything,riseshia/railsguides.kr,felipecvo/rails,voray/rails,kamipo/rails,shioyama/rails,esparta/rails,richseviora/rails,arunagw/rails,fabianoleittes/rails,brchristian/rails,gavingmiller/rails,gcourtemanche/rails,vipulnsward/rails,fabianoleittes/rails,Erol/rails,kddeisz/rails,yawboakye/rails,mathieujobin/reduced-rails-for-travis,shioyama/rails,hanystudy/rails,Vasfed/rails,georgeclaghorn/rails,mohitnatoo/rails,illacceptanything/illacceptanything,Spin42/rails,palkan/rails,schuetzm/rails,yasslab/railsguides.jp,richseviora/rails,gfvcastro/rails,MichaelSp/rails,betesh/rails,gcourtemanche/rails,iainbeeston/rails,kddeisz/rails,mijoharas/rails,schuetzm/rails,yawboakye/rails,stefanmb/rails,yhirano55/rails,Spin42/rails,MichaelSp/rails,Edouard-chin/rails,printercu/rails,repinel/rails,vassilevsky/rails,kachick/rails,shioyama/rails,marklocklear/rails,Envek/rails,voray/rails,elfassy/rails,xlymian/rails,riseshia/railsguides.kr,rails/rails,MSP-Greg/rails,illacceptanything/illacceptanything,ledestin/rails,yalab/rails,pschambacher/rails,illacceptanything/illacceptanything,untidy-hair/rails,rossta/rails,richseviora/rails,kirs/rails-1,arjes/rails,arjes/rails,arunagw/rails,kmayer/rails,bradleypriest/rails,tijwelch/rails,Spin42/rails,starknx/rails,samphilipd/rails,tgxworld/rails,coreyward/rails,shioyama/rails,illacceptanything/illacceptanything,esparta/rails,Sen-Zhang/rails,yhirano55/rails,assain/rails,illacceptanything/illacceptanything,eileencodes/rails,untidy-hair/rails,rbhitchcock/rails,sealocal/rails,tjschuck/rails,repinel/rails,jeremy/rails,koic/rails,georgeclaghorn/rails,yahonda/rails,ngpestelos/rails,yalab/rails,eileencodes/rails,bogdanvlviv/rails,yalab/rails,kmcphillips/rails,88rabbit/newRails,notapatch/rails,pvalena/rails,matrinox/rails,aditya-kapoor/rails,palkan/rails,mtsmfm/rails,mtsmfm/railstest,yhirano55/rails,georgeclaghorn/rails,vassilevsky/rails,sergey-alekseev/rails,MSP-Greg/rails,ledestin/rails,BlakeWilliams/rails,repinel/rails,untidy-hair/rails,Edouard-chin/rails,deraru/rails,arjes/rails,flanger001/rails,bolek/rails,rails/rails,notapatch/rails,yawboakye/rails,illacceptanything/illacceptanything,b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