Factory methods for IsEqual and IsSame matchers

[ghostwriter]

Would a PR adding a factory method for new IsEqual and IsSame matchers to Mockery be welcomed, similar to how Mockery::any() exist? i.e.

class Mockery {
    public static function equal($other) {
        return new IsEqual($other);
    }
}

Originally posted by @oprypkhantc in #1276 (comment)

[oprypkhantc]

Awesome, thank you :)