split ruby_curl_easy_new function into separate allocate and initiali…

[gcz1]

Version 0.9.4 does not allow a subclass to have different number or order of arguments to the base class.

E.g.

`class Derived < Curl::Easy
def initialize(url,foo,bar)
super(url)
end
end

c = Derived.new(nil,1,2)`

gives the following error:

in `new': wrong number of arguments (given 3, expected 0..1) (ArgumentError)

This modification splits ruby_curl_easy_new() into separate allocate and initialize functions
which allows the above code to work.

note some differences are just my editor removing trailing blanks from lines.