Log Message:
Update to Dovecot 1.1beta7.

Changes since beta6:

 - Beginnings of unit tests
 - Message parsing fixes
 - Cache file handling fixes

Known bugs:

 - Cache file doesn't keep track of how much it contains deleted data, which
   means it could grow infinitely. This worked at some point, so I'm not sure
   what I did to break it. I'll figure it out later.
 - Apparently for some use cases v1.1 is still slower (about 2x) than v1.0.
   Probably more or less specific to NFS + mmap_disable=yes.