For now it can only get the contents of a paste.

fillobj was only called when getting previously fetched objects in
interactive mode.
This probably wasn't detected because most get_* backend functions
usually fill a lot of fields by themselves.

check_domain was not used anywhere and was bugged (the domain argument
was ignored in favor of self.DOMAIN).
The check_url decorator checks if the URL can be handled, if not it will
return None. The idea is to avoid making unnecessary requests.

* Do not check for the domain if it is empty in the Browser class
* Better check of the domain (actually parse the URL domain)
* Add docstring

Like most other backends, with the id2url decorator.

Signed-off-by: Pierre Mazière <pierre.maziere@gmail.com>
Signed-off-by: Romain Bignon <romain@peerfuse.org>

Signed-off-by: Romain Bignon <romain@peerfuse.org>

I don't want to clog pastebin's database with my unit tests!