for expect_with :minitest, skip method still works.

Fixes #1820
Updated travis build scripts (from rspec-dev)
Merge pull request #1823 from rspec/update-travis-build-scripts-2014-12-29-for-master

Updates from rspec-dev (2014-12-29)
expect_with :minitest, skip via include
Merge pull request #1822 from jrochkind/minitest_with_skip

for expect_with :minitest, skip method still works.
Changelog for #1822.
Create only one example group alias per name.

It's possible to register the same alias multiple times. The last alias
defined, including it's metadata, will be used. This prevents the
aliases from being defined multiple times on `RSpec` and the other main
objects.

This also prevents a `NameError` when the second duplicate alias is
undefined when the DSL is no longer globally exposed.

Fix #1824
Note fix in the Changelog.

[ci skip]