asset guide, match application.rb snippets to the generated file [ci skip]

`if defined?(Bundler)` is no longer used in our current application.rb
Fix AM testcase break with mail 2.5.4. It seems that AM's testcase was wrong.
"normalize_callback_params" doesn't require name param
Eliminate minitest warnings

https://github.com/seattlerb/minitest/commit/9a57c520ceac76abfe6105866f8548a94eb357b6#L15R8
Merge pull request #10659 from vipulnsward/normalize_param2

"normalize_callback_params" doesn't require name param
Missing ending ``` at 14.2 Merging of scopes

http://edgeguides.rubyonrails.org/active_record_querying.html#merging-of-scopes
Merge pull request #10688 from elgalu/master

Missing ending ``` at 14.2 Merging of scopes
Fix typo in test name and documentation
Fix wrong `case_sensitive` in uniqueness validity test
Merge pull request #10691 from vipulnsward/typo_fix_ar_1

Fix typo in test name and documentation
Merge pull request #10692 from vipulnsward/fix_test_3

Fix wrong `case_sensitive` in uniqueness validity test
Merge pull request #10646 from kennyj/fix_am_20130517

Fix ActionMailer testcase break with mail 2.5.4.
No need CHANGELOG entry for a test fix

[ci skip]
Add has_named_route? to the mapper API
Spelling correction in Upgrading Guide

Fixes spelling of 'erratta' to 'errata'
Merge pull request #10697 from zhubert/patch-1

Spelling correction in Upgrading Guide [ci skip]
pass where values to the helper function rather than rely on internal state
save the where values in variables so we don't need to look them up all
the time
change method name to reflect what it actually does.
eliminate some conditionals