dovecot: optionally use clucene.

References #26100.
Closes #26102.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
dovecot: cleanup caveats.
percona-server 5.6.15-rel63.0

Closes #26131.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
Merge branch 'master' of https://github.com/Homebrew/homebrew

:s

:q
:quit

:

* 'master' of https://github.com/Homebrew/homebrew:
  percona-server 5.6.15-rel63.0
  dovecot: cleanup caveats.
  dovecot: optionally use clucene.
node: stable version is allowed to be built with python 2.6