moving transform objects and allow iframes lists to object properties
extract method on remove sandbox attribute code
making sure all if blocks have curly braces. too easy to miss one without
adding default value for remove unknown iframes
extract method refactor for get src attribute code
missed a use of _getSrcAttribute. removing duplication
extract method refactor for "is valid iframe url" test to make logic more clear
Merge pull request #11 from fentie/master

Bit of refactoring