Add hint to error message of task db:migrate:down
Getting started guide fixes & Explain X-SendFile a little better, with links

Explain how form_for :article is able to pull in the properties of @article
Make it clear that article_id is generated due to the association set up

Add link to the rails function that uses X-Sendfile.
Add links to apache and nginx docs for the header
remove unused fixtures from sqlite3 test cases
fix guide active_support_core_extensions. add Note to String#indent [ci skip]
updated Travis build status image url
Merge pull request #14058 from lantoli/master

updated Travis build status image url
Merge pull request #14059 from tbpgr/guides_active_support_core_ext

[Guides] fix guide active_support_core_extensions. add Note to String#indent [ci skip]
Merge pull request #14057 from rajcybage/Ar_remove_unnecessary_fixtures

Remove unused fixtures from sqlite3 test case
Merge pull request #14048 from pcreux/better-error-message-db-migrate-down

Add hint to error message of task db:migrate:down
fix path shown in mailer's templates
Merge pull request #14060 from kassio/master

Fix path shown in mailer's templates
Add verb to sanitization note
Merge pull request #14061 from davejachimiak/add_verb_in_guides

Add verb to sanitization note
remove scope_chain delegate
remove chain delegate
remove railties changes. fixes #14054

Squashed commit of the following:

commit 96991e8e919edfb20cc4120bca4e36ed51175d57
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:29:24 2014 -0800

    Revert "gems can be added or skipped from the template"

    This reverts commit 8beb42cfbc41753ae4dbb91e16abcd1fb7d00356.

    Conflicts:
    	railties/lib/rails/generators/rails/app/app_generator.rb
    	railties/test/generators/app_generator_test.rb

commit 35599c0e657245ef14ac0f28c9189ad16acf40e6
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:26:53 2014 -0800

    Revert "oops, template replay needs to happen after bundle. :orz:"

    This reverts commit 9104702be61253f9448ca070a22fc86bb4299555.

    Conflicts:
    	railties/lib/rails/generators/rails/app/app_generator.rb

commit f519c3902c313db8e906a49251c91643b8e6499e
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:51 2014 -0800

    Revert "only ask for these ivars if the target responds to them"

    This reverts commit 656d412546cd97d5660c634c2a41c799d3f9e211.

commit aa524a9428e3e4c45fe221f10a66a08efb827ab5
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:39 2014 -0800

    Revert "refactor generator tests to use block form of Tempfile"

    This reverts commit 65251820ef0ab7f3cffb38130de3dd41af8d72be.

commit 7d3740549fa4dfa62e3761f8d4bc6d6d441256e7
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:25 2014 -0800

    Revert "add a more restricted codepath for templates fixes #13390"

    This reverts commit 2875b4a66e38e4333da887a4afbed33358999298.

commit 525df0af1001918986cdfce59539fd2d52c4f32c
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:11 2014 -0800

    Revert "add a send so `apply` can be called.  Fixes #13510"

    This reverts commit c5034d60dba0cd31a6a8c612ee35d63b8127793a.
remove klass delegator
remove the reflection delegate
clean up add_constraints signature
pass the tracker down the stack and construct it in the scope method