Added handling for AlreadyColsedException and fixed executor cleanup
(cherry picked from commit 9e3060dd3580d2e027d8c91e263efb29401b72bb)
Introducting MasterCaches and Buffer perf. fixes

Fixes #115

Squashed commit of the following:

commit 074aa7569e29174e0d79c1fa15a0302bda70027e
Author: Lennart Koopmann <lennart@socketfeed.com>
Date:   Sat Mar 2 21:40:55 2013 +0100

    finished masterbuffers

commit 58ce0b747166e1988a90c96f4d1e935f0202a46a
Author: Lennart Koopmann <lennart@socketfeed.com>
Date:   Sat Mar 2 18:04:57 2013 +0100

    current state of masterbuffer development
Metrics for MasterCacheWorkers

Fixes #118
Implment HTML email transport with optional links to stream messages
Replace Commons Email with direct javax.mail calls, reusing sessions and transports where possible for lower overhead
Add support for smtps protocol
(cherry picked from commit 851122dcdd5206034d4d214e125ef38944393f58)
Upgrade graylog2-plugins, pull request cleanup

fixes #113
bumped version to 0.11.0