Enumerable#every and #some should always return booleans

Batman's #every and #some methods do not correctly implement the ES5 specifications for the matching
native array methods. While the specifications state that these methods should always return
booleans, Batman's versions will return the last truthy value.

Array#every http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.16
Array#some  http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.17
Merge pull request #974 from davidcornu/fix-every-and-some

Enumerable#every and #some should always return booleans