Added check for unit attribute of date item, if type is recurrent
Added additional test case for unit check in date item
Added unit presence validation for recurrent price items and generator tag added by default in maker
Updated automatic value for generator tag
Compatibility with 1.9.2 fix
Moved push method directly to element instead of including and fixed request reference overwriting bug
Refactored Element class
Removed channel class
Fixed version string in default generator value
Updated README.md and set version to 0.9.0