Fix failing tests related to where values change to strings

Introduced in 5dc2e3531babcbdc165884d1a47cbcd13455522d.
change from blank? to empty? on obvious string values  to save extra method calls
Merge pull request #9784 from vipulnsward/change_from_blank_to_empty_on_string

Change from blank? to empty? on obvious string values  to save extra calls
Revert "Merge pull request #9784 from vipulnsward/change_from_blank_to_empty_on_string"

This reverts commit 9c4c05fc82e997b722dec4068c3aa27eaee69eb8, reversing
changes made to 4620bdcefd0c88905a005f191496df887877b8f3.

Reason: They're not completely interchangeable, since blank? will also
check for strings containing spaces.
Use @app_env_config instead of @env_config

Check pull request #9789 for more information.
Initialize @app_env_config now that the var name has changed

Check 862389c9537dbb6f65fd26c4325e07607ed437b5 for more background.
drop an unused hash; change slang to SPECIAL
Merge pull request #9792 from vipulnsward/drop_unused_hash

drop an unused hash; change slang to SPECIAL
Fix warning: mismatched indentatmmismatched indentations at 'end' with 'def'
Merge pull request #9800 from kennyj/fix_warning_20130319

Fix warning: mismatched indentatmmismatched indentations at 'end' with 'def'
The repair_validations helper was not working correctly before because
it only cleared the validations that created :validate callbacks. This
didn't include the validates created by validates_with, so I've added a
method to clear all validations.
Merge pull request #9363 from wangjohn/fix_repair_validations

Fixed the repair_validations helper method.
remove unused payloads in blocks in caching instrumentation
Fix improperly configured host in generated urls

If the host in `default_url_options` is accidentally set with a protocol such as 

```
host: "http://example.com"
``` 

then the generated url will have the protocol twice `http://http://example.com` which is not what the user intended. Likely they wanted to define a host `host: "example.com"` and a `protocol: "http://"` but did not know the convention.

This may not the most common problem, but when it happens it can go undetected for a while. I accidentally added `http://` out of habit recently only to find all the links in my emails were broken after deploying a demo site to production. Rather than allow this accident go undetected, we can fix the problem in line by properly setting the protocol and host.


I was able to find this related question on stack overflow: http://stackoverflow.com/questions/5878329/rails-3-devise-how-do-i-make-the-email-confirmation-links-use-secure-https-n where the answer was highly upvoted.

This is based off of work in #7415 cc/ @pixeltrix

ATP Action Mailer and Action Pack
fix sentence [ci skip]
Merge pull request #9811 from neerajdotname/fix-secret-token-sentence

fix sentence [ci skip]
Calling find() on an association with an inverse will now check to see
if the association already holds that record in memory before checking
the database for the specified ids.
Merge pull request #9807 from vipulnsward/remove_unused_payloads

remove unused payloads in blocks in caching instrumentation
Merge pull request #9529 from wangjohn/find_on_inverse_of_bugfix_9470

Find() on an association with an inverse will now scan existing in-memory records
Fix guides error on error class name

The error that's raised in case the required key is missing it's actually `ActionController::ParameterMissing` not `ActionController::MissingParameter`. It's important to fix so that people reading the guides knows what error to rescue from when needed.