Add link to minitest rdoc & github
[ci skip] Use appropriate mailer syntax.

Reference: https://github.com/rails/rails/commit/f7e4362011ceb1317fd401125d48d7ccb9a1079c
[ci skip] Remove duplicated last! section.

Reference: https://github.com/rails/rails/commit/d4fd0bd17709735ac91e434c94fe99429f078c6e

cc @schneems
Performed Returns true if redirect/render has happened
[ci skip] Normalize all localhost linking.
Added Object#self which returns the object itself
Rename Object#self to Object#itself to have parity with matz sanctioned method name for Ruby 2.2
Rename tests too
always return a string from find_script_name

this allows us to avoid nil checks on the return value
just set the host, no need for another hash allocation / merge!
copy edits[ci skip]
Merge branch 'master' of github.com:rails/docrails

Conflicts:
	guides/source/testing.md
Add an :if_exists option to drop_table