Add html_escape note to CHANGELOG

This was added to all other branches, but 3-1 missed the entry.

3-0-stable: 954e26263681896312b9133e07db3123e8b13c03
3-2-stable: ae2383d90a9646e36c8b5d92801fba284ea62ec0
master: 5c07be5f7fb7e6417c09751c7fb9bb98a63d9917
Remove warning when using html_escape with Ruby 1.9.

Closes #7323
Use benchmark/ips to measure AR performance

This means we can more easily compare numbers, and we don't have to
specify a single N for all reports, which previously meant that some
tests were running many more/fewer iterations than necessary.

Conflicts:
	Gemfile
	activerecord/examples/performance.rb
Increase benchmark time to 20 seconds.

I think that 5 seconds was a bit low for our purposes.

Also enable it to be configured via env vars.

We also need to scale the number of records up/down depending on how
long we're running the benchmark for.

Conflicts:
	activerecord/examples/performance.rb
CHANGELOGs are now per branch

Check 810a50d for the rationale.
Ensure association preloading properly merges default scope and association conditions
Require ActionController::Railtie in the default middleware stack.

This will make possible to do a frameworkless initialization since the
the default middleware stack is self contained.
test for 8018
do not install ruby-prof on Ruby 2.0
Update xml serialization tests to reflect a change in builder

Due to a change in builder, nil values now generates closed tags,
so instead of this:

    <pseudonyms nil=\"true\"></pseudonyms>

It generates this:

    <pseudonyms nil=\"true\"/>

Document this change in Rails so that people can track it down easily if
necessary.

Changes in Active Model, Active Record and Active Support tests.

Cherry-pick of d65adc7, 77dd3be and 146eaf3. Fix build.
Be a bit less conservative with mysql in adapter

This will allow the new mysql 2.9.0 to be used, fixing our test issues.
updating changelogs
CVE-2012-5664 options hashes should only be extracted if there are extra parameters
bumping version to 3.1.9
Merge remote-tracking branch 'rails/3-1-stable' into 3-1-stable