Removed Supported header from MWI subscription

Ignore-this: f521730915417deee880ad7216b1c845

darcs-hash:20100901215323-56b4d-9a11b584baed1e7fd2c47a1cd0e719ddbf894932
Avoid refreshing subscription if not NOTIFY was received after an un-SUBSCRIBE

Ignore-this: c4a8d36103fdb008f0fa0ee31e0b320a

darcs-hash:20100902101141-56b4d-93733b9dcec6c907ee34f0c9584e4b85887af349