Substitute `match` method for the `=~` operator

The `match` method generates a MatchData object, making it slower than
the `=~` operator [1]. Since this MatchData object is not being used, it
makes sense to switch to `=~`.

[1]: http://stackoverflow.com/a/11908214/1160916
Fix testing on Ruby 2.1.2

Changes include:

* Using Minitest::Test instead of Test::Unit

* Updating mocha to the latest version

* Using test_construct since test-construct is no longer being maintained

* Fixing 3 broken tests
Add ruby 2.1.2 to travis testing file
Fix whitespace