- Add zip_safe flag

- Add a warning to prepare for the merge of #81
- Update existing deprecation warnings

If we get a connection error during Site init, it's better to let the
exception through directly since it can well be due to a hostname typo.

The flag has always been named 'messages', not
'message', but has been documented wrongly.

Adding pageid, contentmodel, pagelanguage, restrictiontypes as attributes of Page

Thoses attributes were only accessible through private _info dict.

pageid was only accessible through the 'private' _info dict.

Add support for querying the CheckUser log

Handling requests exceptions is the responsibility of `Site.raw_call()`,
not `Site.upload()`

Add a null handler to prevent 'No handlers could be found for logger
"mwclient.*"' warnings. This seems to be good practice for libraries.

When rctoponly is set only changes which are the latest revision are listed.

fix PageList API arg passing to GeneratorList

PageList wasn't adding the 'g' prefix to API arguments it
passes to GeneratorList, and GeneratorList doesn't do that
itself. This fixes it.

Adds six as requirement. It solves "ImportError: No module named six"