Wrap arguments in parens to quiet Ruby warnings.

This fixes the "`&' interpreted as argument prefix" Ruby warnings.
Fix the circular dependency between equivalent-xml and matchers.

In order to maintain current autoload-RSpec matchers functionality when
requiring the equivalent-xml library, we must also ensure that
equivalent-xml is not loaded at the time the matchers are loaded prior
to requirement. Otherwise, library requires matchers, matchers require
library.
Remove the RSpec file pattern declaration since it is the default.

This also fixes an incompatibility with RSpec 3.1.
Merge pull request #26 from nbibler/circular-dependency