Update ChangeLog with 0.6.1 release date.
Update ChangeLog with 0.6.1 release date.

gcarranza/couchdb-python,ssaavedra/couchdb-python,erikdejonge/rabshakeh-couchdb-python-progress-attachments,oliora/couchdb-python,jur9526/couchdb-python,hdmessaging/couchbase-mapping-python