Update upgrading guide with ActionDispatch::BestStandardsSupport removal
Merge pull request #9178 from robertomiranda/best-standard-support-guide

Update upgrading guide with ActionDispatch::BestStandardsSupport removal [ci skip]
Ignore .ruby-version
Merge pull request #9192 from adammck/ignore-dot-ruby-version

Ignore .ruby-version
Enable hstore extensions on tests if it is not enabled and database supports it
Update .gitignore

Get rid of old .rvmrc and .rbenv-version files.