added a bunch of new methods for the cheerio

Please help review it and add all these changes to the main repository

#  Methods added for the attributes:
> css

# Methods added for the traversing:
> add
> index
> has
> not
> is
> contents

# Methods added for the manipulation
> prependTo
> hide
> show
> width
> height
> toggle
> toggleClass
> forEach
> get
> size
> wrap
> wrapAll
> wrapInner
> unwrap
 
# Methods added for the form
> serialize
> serializeArray