be more specific about csrf token and ajax - not whitelisted outside of jquery-rails [ci skip]
Fix breakage in XmlMini

- Boolean parsing breaks on non strings (i.e. integer 1|0)
- Symbol parsing breaks on non strings.
- BigDecimal parsing breaks due to missing require.
- Update changelog.
Fixed typo [ci skip]

singular is more suited to
change to "check out"
e-mail => email, and subject/verb agreement
add punctuation
Remove duplicate configuration option for ActiveSupport [ci skip]

Fixes rails/rails#13732
psql implementation of #index_name_exists?
`requies` => `requires`
`easiy` => `easy`
`framwork` => `framework`
Remove old comments about suppressing warnings.
Replace Post with Article in getting started guide [ci skip]

- Used Article model instead of Post as it may confuse with 'post'
  requests
- Tried to wrap the guide to 80 chars lines as much as possible.
- Removed unused image
- Fixes #13764
Add CreateMigration action

This Thor-action isolates the logic whether to (over-)write migration and
what is shown to the user. It's modelled after Thor's CreateFile-action.

This solves the issue that removing a non-existing migration, tried to
remove the template-path (#13588).

Related issues: #12674
Enhance errors while retrieving database config

Right now if there is an error retrieving database configuration the intent of the error (what the code was trying to do while you got the error) could be more explicit. 

Instead of this error:

```
Invalid DATABASE_URL: nil
(erb):9:in `rescue in <main>'
(erb):6:in `<main>'
/Users/schneems/.rbenv/versions/2.1.0/lib/ruby/2.1.0/erb.rb:850:in `eval'
/Users/schneems/.rbenv/versions/2.1.0/lib/ruby/2.1.0/erb.rb:850:in `result'
/Users/schneems/Documents/projects/rails/railties/lib/rails/application/configuration.rb:98:in `database_configuration'
/Users/schneems/Documents/projects/rails/activerecord/lib/active_record/railtie.rb:41:in `block in <class:Railtie>'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `instance_exec'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `block in run_tasks_blocks'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `each'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `run_tasks_blocks'
/Users/schneems/Documents/projects/rails/railties/lib/rails/application.rb:339:in `block in run_tasks_blocks'
/Users/schneems/Documents/projects/rails/railties/lib/rails/engine/railties.rb:13:in `each'
```

I propose we issue this error:

```
Cannot load `Rails.application.database_configuration`:
Invalid DATABASE_URL: nil
(erb):9:in `rescue in <main>'
(erb):6:in `<main>'
/Users/schneems/.rbenv/versions/2.1.0/lib/ruby/2.1.0/erb.rb:850:in `eval'
/Users/schneems/.rbenv/versions/2.1.0/lib/ruby/2.1.0/erb.rb:850:in `result'
/Users/schneems/Documents/projects/rails/railties/lib/rails/application/configuration.rb:98:in `database_configuration'
/Users/schneems/Documents/projects/rails/activerecord/lib/active_record/railtie.rb:41:in `block in <class:Railtie>'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `instance_exec'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `block in run_tasks_blocks'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `each'
/Users/schneems/Documents/projects/rails/railties/lib/rails/railtie.rb:237:in `run_tasks_blocks'
/Users/schneems/Documents/projects/rails/railties/lib/rails/application.rb:339:in `block in run_tasks_blocks'
/Users/schneems/Documents/projects/rails/railties/lib/rails/engine/railties.rb:13:in `each'
```
Added some style changes in asset pipeline documentation
Fixing issue with activerecord serialization not being able to dump a record after loading it from YAML - fixes #13861
Merge pull request #13876 from sowjumn/master

Added some style changes in asset pipeline documentation
Merge pull request #13867 from mauricio/bug-13861

Fixing issue with activerecord serialization not being able to dump a record after loading it from YAML - fixes #13861
Aesthetic