Add missing require in ActionMailer
Add missing require in ActionMailer

Without this, Action Mailer doesn't work like it used to on version 4.
The following snippet fails since version 5:

    > require 'action_mailer'
    > ActionMailer::Base
    NameError: uninitialized constant ActiveSupport::Rescuable

mechanicles/rails,schuetzm/rails,baerjam/rails,koic/rails,Envek/rails,repinel/rails,tjschuck/rails,ttanimichi/rails,flanger001/rails,notapatch/rails,shioyama/rails,esparta/rails,alecspopa/rails,MSP-Greg/rails,kirs/rails-1,schuetzm/rails,utilum/rails,betesh/rails,yalab/rails,rails/rails,fabianoleittes/rails,illacceptanything/illacceptanything,yhirano55/rails,alecspopa/rails,felipecvo/rails,vipulnsward/rails,ngpestelos/rails,gfvcastro/rails,illacceptanything/illacceptanything,betesh/rails,repinel/rails,palkan/rails,xlymian/rails,yahonda/rails,palkan/rails,yasslab/railsguides.jp,Edouard-chin/rails,printercu/rails,georgeclaghorn/rails,mathieujobin/reduced-rails-for-travis,kmayer/rails,xlymian/rails,yalab/rails,gfvcastro/rails,brchristian/rails,Edouard-chin/rails,printercu/rails,ledestin/rails,jeremy/rails,flanger001/rails,yahonda/rails,vipulnsward/rails,assain/rails,yawboakye/rails,kamipo/rails,eileencodes/rails,Envek/rails,mohitnatoo/rails,prathamesh-sonpatki/rails,bogdanvlviv/rails,maicher/rails,palkan/rails,maicher/rails,joonyou/rails,odedniv/rails,joonyou/rails,gcourtemanche/rails,BlakeWilliams/rails,Erol/rails,iainbeeston/rails,deraru/rails,iainbeeston/rails,travisofthenorth/rails,pschambacher/rails,kddeisz/rails,pvalena/rails,mechanicles/rails,MSP-Greg/rails,hanystudy/rails,ttanimichi/rails,Sen-Zhang/rails,matrinox/rails,travisofthenorth/rails,kddeisz/rails,bradleypriest/rails,Erol/rails,gfvcastro/rails,fabianoleittes/rails,xlymian/rails,eileencodes/rails,kmcphillips/rails,koic/rails,fabianoleittes/rails,rails/rails,Stellenticket/rails,kmayer/rails,flanger001/rails,yasslab/railsguides.jp,yawboakye/rails,pvalena/rails,yawboakye/rails,BlakeWilliams/rails,illacceptanything/illacceptanything,fabianoleittes/rails,vipulnsward/rails,gcourtemanche/rails,pvalena/rails,yalab/rails,jeremy/rails,printercu/rails,Erol/rails,bradleypriest/rails,illacceptanything/illacceptanything,aditya-kapoor/rails,mijoharas/rails,yalab/rails,yhirano55/rails,illacceptanything/illacceptanything,assain/rails,tgxworld/rails,schuetzm/rails,kmayer/rails,yasslab/railsguides.jp,yhirano55/rails,aditya-kapoor/rails,kaspth/rails,gauravtiwari/rails,gfvcastro/rails,odedniv/rails,deraru/rails,georgeclaghorn/rails,georgeclaghorn/rails,brchristian/rails,Stellenticket/rails,kmcphillips/rails,felipecvo/rails,pvalena/rails,alecspopa/rails,schuetzm/rails,yahonda/rails,starknx/rails,betesh/rails,printercu/rails,koic/rails,tjschuck/rails,rafaelfranca/omg-rails,jeremy/rails,kamipo/rails,untidy-hair/rails,georgeclaghorn/rails,Sen-Zhang/rails,illacceptanything/illacceptanything,tjschuck/rails,esparta/rails,joonyou/rails,rails/rails,tgxworld/rails,tgxworld/rails,assain/rails,felipecvo/rails,prathamesh-sonpatki/rails,gcourtemanche/rails,utilum/rails,bogdanvlviv/rails,betesh/rails,yasslab/railsguides.jp,pschambacher/rails,illacceptanything/illacceptanything,odedniv/rails,deraru/rails,Edouard-chin/rails,jeremy/rails,maicher/rails,eileencodes/rails,yawboakye/rails,arunagw/rails,BlakeWilliams/rails,iainbeeston/rails,Envek/rails,eileencodes/rails,kmcphillips/rails,kddeisz/rails,notapatch/rails,kirs/rails-1,mathieujobin/reduced-rails-for-travis,arunagw/rails,travisofthenorth/rails,lucasmazza/rails,esparta/rails,brchristian/rails,lucasmazza/rails,untidy-hair/rails,travisofthenorth/rails,hanystudy/rails,kamipo/rails,matrinox/rails,untidy-hair/rails,bogdanvlviv/rails,kddeisz/rails,joonyou/rails,Stellenticket/rails,kaspth/rails,tgxworld/rails,yhirano55/rails,illacceptanything/illacceptanything,palkan/rails,shioyama/rails,BlakeWilliams/rails,mechanicles/rails,ngpestelos/rails,notapatch/rails,illacceptanything/illacceptanything,shioyama/rails,illacceptanything/illacceptanything,Erol/rails,starknx/rails,pschambacher/rails,baerjam/rails,Vasfed/rails,vipulnsward/rails,mijoharas/rails,utilum/rails,deraru/rails,lcreid/rails,mechanicles/rails,lcreid/rails,Sen-Zhang/rails,illacceptanything/illacceptanything,baerjam/rails,tjschuck/rails,mohitnatoo/rails,MSP-Greg/rails,arunagw/rails,repinel/rails,mohitnatoo/rails,Vasfed/rails,Stellenticket/rails,EmmaB/rails-1,baerjam/rails,rails/rails,bradleypriest/rails,Envek/rails,illacceptanything/illacceptanything,lcreid/rails,repinel/rails,gauravtiwari/rails,lcreid/rails,bogdanvlviv/rails,iainbeeston/rails,assain/rails,shioyama/rails,EmmaB/rails-1,prathamesh-sonpatki/rails,EmmaB/rails-1,arunagw/rails,hanystudy/rails,kaspth/rails,lucasmazza/rails,aditya-kapoor/rails,mijoharas/rails,mohitnatoo/rails,untidy-hair/rails,prathamesh-sonpatki/rails,ngpestelos/rails,kmcphillips/rails,starknx/rails,ttanimichi/rails,flanger001/rails,esparta/rails,ledestin/rails,kirs/rails-1,illacceptanything/illacceptanything,illacceptanything/illacceptanything,Vasfed/rails,illacceptanything/illacceptanything,rafaelfranca/omg-rails,rafaelfranca/omg-rails,Vasfed/rails,MSP-Greg/rails,utilum/rails,ledestin/rails,yahonda/rails,Edouard-chin/rails,notapatch/rails,mathieujobin/reduced-rails-for-travis,aditya-kapoor/rails,matrinox/rails,gauravtiwari/rails