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
Remove mentions of "app" from http request docs [ci skip]
Merge pull request #9794 from schneems/schneems/email-host

Fix improperly configured host in generated urls
Changed the call to .sort.last to .max when computing the migration version. You
do not actually need to sort everything (incurs more cost than just a
simple max).
Commas aren't comas.

Type a fixo.
Merge pull request #9817 from knewter/fix-test-case-name-typo-in-ar

Commas aren't comas.
Merge pull request #9818 from wangjohn/sort_last_to_max_in_migration_version

Changed the call to .sort.last to .max when computing the migration version
Fix some typos in AR- CHANGELOG, tests, method doc. fixed
Fix a typo
Merge pull request #9825 from rShetty/patch-1

Fix a typo
Merge pull request #9821 from vipulnsward/fix_typos_in_AR

Fix some typos in AR- CHANGELOG, tests, method doc. fixed