'Check if a JID supports a given feature.
Return values:
True  -- The feature is supported
False -- The feature is not listed as supported
None  -- Nothing could be found due to a timeout
Arguments:
jid      -- Request info from this JID.
node     -- The particular node to query.
feature  -- The name of the feature to check.
local    -- If true, then the query is for a JID/node
combination handled by this Sleek instance and
no stanzas need to be sent.
Otherwise, a disco stanza must be sent to the
remove JID to retrieve the info.
cached   -- If true, then look for the disco info data from
the local cache system. If no results are found,
send the query as usual. The self.use_cache
setting must be set to true for this option to
be useful. If set to false, then the cache will
be skipped, even if a result has already been
cached. Defaults to false.
ifrom    -- Specifiy the sender\'s JID.'

def supports(self, jid=None, node=None, feature=None, local=False, cached=True, ifrom=None):

    data = {'feature': feature, 'local': local, 'cached': cached}
    return self.api['supports'](jid, node, ifrom, data)
