Change all `MiniTest` to `Minitest` since, `MiniTest` namespace has been renamed to `Minitest`
Ref: https://github.com/seattlerb/minitest/blob/master/History.txt
document how to access mail previews. [ci skip]

/cc @pixeltrix
Always point to latest rbx and jruby in travis
make clear that config/secrets.yml passes through ERB and therefore supports ENV
Fix to_param when attribute has multibyte character
Merge pull request #13386 from rono23/fix-to-param

Fix to_param when attribute has multibyte character
Unused classes in test case
Fix PostgreSQL range tests

The changes in c4044b2 meant the tests would error on a fresh DB.
Merge pull request #13366 from vipulnsward/minitest-namespace-change

Change all `MiniTest` to `Minitest`
set encoding UTF-8 for accepting multibyte character
Fix typo: data --> date
Merge pull request #13399 from ghiculescu/patch-1

Fix typo: data --> date [ci-skip]
Merge pull request #13398 from kuldeepaggarwal/build-fixes

set encoding UTF-8 for accepting multibyte character
fix typos and grammar mistake [ci skip]
Merge pull request #13400 from nishant-cyro/docs

fix typos and grammar mistake [ci skip]
Unused classes in AS tests
Unused classes in AMo tests
Merge pull request #13393 from matthewd/fix_pg_range_tests

Fix PostgreSQL range tests on fresh DB

Correcting the name of the table we're creating is self-explanatory.

But we must also move away from the low IDs, because we're not touching the freshly-created primary key sequence; when the time comes, @new_range will be assigned an ID of 1.
Update configuring guide with I18n options regarding available locales

Add information about 'available_locales' and 'enforce_available_locales'
to the configuring guide.

Closes #13202. [ci skip]
Fix asserting the correct exception message in dependencies test

In Minitest, the second argument of assert_raise(s) accepts a string as
the message that should be shown in case of a failure in the assertion
(eg nothing was raised when it should), and not the exception message to
be matched.

To do that we need to save the exception returned from assert_raise(s)
into a local variable and check for the exception message using it.