Successful test on RSpec 3.0

## Motivation

Run tests on RSpec 2.99, display `Deprecation Warnings`:

```
$ bundle list | grep rspec
 * rspec (2.99.0)
 * rspec-core (2.99.0)
 * rspec-expectations (2.99.0)
 * rspec-mocks (2.99.0)
$ bundle exec rake spec
...................
Deprecation Warnings:
The semantics of `RSpec::Core::Pending#pending` are changing in
RSpec 3.  In RSpec 2.x, it caused the example to be skipped. In
RSpec 3, the rest of the example will still be run but is expected
to fail, and will be marked as a failure (rather than as pending)
if the example passes.

(skip...)

--------------------------------------------------------------------------------

Using `s` as a shortcut for the DocumentationFormatter is deprecated. Use `d`, `doc`, or `documentation` instead.

(skip...)
```
So, run tests on RSpec 3.0, failed because of the above problems.

## Solution

See commits