httplib does not handle the download as expected.
The implementation of urlretrieve is much better and consistent, it does
the download
writing in chunks instead of loading all the file content into memory.

Also, the httplib can easily break the file content, if the client does
not
handle it. And this lib must be very simple.

The timeout is not in favor of httplib GET method.

Based in the above reasons, httplib was replaced to
urlretrieve, once there is no reason to reimplement what already exists.

Because the user can just use the 'select' method to retrieve the information
from shadir server.

Otherwise, all the connections would still alive and this is not a good
behavior.

Once we need to close the connections it is not possible to return the
content of getresponse method, the method read would return an empty
string instead of the correct data.

And also the data returned by shadir is a json content,
to reach a better usage of libnetworkcache the data returned must be
loaded by json library, in other words, it must be a list.

implemented the first version of upload and download methods. Upload is using both server already, shacache and shadir.