specs opacity fix

el.style.opacity returns a string, not a number

http://jsfiddle.net/eLLMT/
Restored original syntax

Restored original syntax in the specs as it was in
https://github.com/mootools/mootools-core/blob/master/Specs/1.2/Element/Element.js#L246

Array.type() is old MooTools and return boolean hear, not 'array'/string

http://jsfiddle.net/nYMWz
Merge pull request #5 from SergioCrisostomo/Array-type-specs-fix

Array type & opacity specs fix