Update Dovecot Pigeonhole plugin to 0.2.2 (goes with Dovecot 2.0.8).

Update Dovecot Pigeonhole plugin to 0.2.2 (goes with Dovecot 2.0.8).

* LDA Sieve plugin: started using Dovecot LDA reject API for the
  reject extension. This means that the LDA reject_reason and
  reject_subject settings now also work for Pigeonhole's LDA Sieve
  plugin.
* Did some work on the new sieve-filter tool. It is mostly
  functional, but it is not finished yet.
* Dovecot change: services' default vsz_limits weren't being enforced
  correctly in earlier v2.0 releases. Now that they are enforced, you
  might notice that the default limits are too low and you need to
  increase them. This problem will show up in logs as "out of memory"
  errors. See default_vsz_limit and service { vsz_limit } settings.
- Imap4flags: fixed segfault bug occurring in multiscript context.
- Added version checking to the ManageSieve settings plugin. This
  plugin was forgotten when the LDA plugin was updated with this
  change in the previous release.
- LDA Sieve plugin: fixed memory leak at deinitialization.