[ci skip] updated 'where' in association documention to new style syntax
Merge pull request #16501 from tomkadwill/update_delete_to_new_style

[ci skip] updated 'where' in association documention to new style syntax
Use string for order argument, fixed from #16501 [ci skip]
Be sure to reset PK name renamed in the test
extract methods and metaprogram less.
Ignore MySQL "SHOW VARIABLES" when counting queries
Perf optimization for `url_for` called w/ Hash

Benchmarking the existing code:

```ruby
{ :only_path => options[:host].nil? }.merge!(options.symbolize_keys)) 
```

Against optimized code, that does not require a new hash or a merge:

```ruby
options = options.symbolize_keys
options[:only_path] = options[:host].nil? unless options.key?(:only_path)
options
```

We see a statistically significant performance gain:

![](https://www.dropbox.com/s/onocpc0zfw4kjxl/Screenshot%202014-08-14%2012.45.30.png?dl=1)

Updated to not mutate incoming parameters
Merge pull request #16504 from schneems/schneems/fix_url_for

Perf optimization for `url_for` called w/ Hash
Spelling errors
Merge pull request #16508 from jbsmith86/master

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