XEP-0065,XEP-0096,XEP-0166,XEP-0235,XEP-0300: file transfer improvments:

huge patch sorry :)

many things are improved by this patch, notably:
- updated to last protocol changes (urn:xmpp:jingle:apps:file-transfer:5 and urn:xmpp:hashes:2)
- XEP-0234: file request implementation
- XEP-0234: methods to parse and generate <file> element (can be used by other plugins easily)
- XEP-0234: range data is now in a namedtuple
- path and namespace can be specified when sending/requesting a file (not standard, but needed for file sharing)
- better error/termination handling
- trigger points to handle file requests by other plugins
- preparation to use file plugins with components

src/memory/cache.py

@@ -32,7 +32,6 @@ class Cache(object):
     """generic file caching"""
 
     def __init__(self, host, profile=None):
-        host = host
         self.profile = profile
         self.cache_dir = os.path.join(
             host.memory.getConfig('', 'local_dir'),