Decode attributes pulled from URI.parse

The RFC indicates that username and passwords may be encoded.
http://tools.ietf.org/html/rfc2396#section-3.2.2

Found this trying to use the mysql://username:password@host:port/db and having special characters in the password which needed to be URI encoded.

Implement HashWithIndifferentAccess#replace so key? works correctly.

Fixing the build.

In the end I think the pain of implementing this seamlessly was not
worth the gain provided.

The intention was that it would allow plain ruby objects that might not
live in your main application to be subclassed and have persistence
mixed in. But I've decided that the benefit of doing that is not worth
the amount of complexity that the implementation introduced.

Add missing require for minitest assertions. Breaks calling 'app' in console otherwise. See 94248ffe.

Update redcarpet dependency

"~> 2.2.2" from "~> 2.1.1". Also converted all hash rockets in the
Gemfile to the 1.9 syntax.

Fix gratuitous use of ternary operator

Pass key to block in cache.fetch on miss

Fix incorrect markdown by removing extra space. [ci skip]

We discussed this on Twitter, seems to be the best option.

changed test case name

activerecord scope.

Related with 5341b849

Remove extra line in Gemfile generated

Conflicts:
	activesupport/lib/active_support/core_ext/hash/slice.rb
	guides/source/active_support_core_extensions.md