Add proper names to some more threads.
Start a test for the Periodicals class.
Not scanning for alerts when message processing is disabled.
Removing debug output.
Using explicit types for Input/OutputCache/OutputBuffer.

This fixes erratic behaviour where the InputCache of the ProcessBuffer
was a different instance than the one injected in other places.
Several providers became obsolete after tagging the
InputCache/OutputCache classes singleton.
explain stream timeout configuration variables in sample config

fixes #610

(cherry picked from commit 74537224f0ba7d10f5e3354759c414d5c2b24263)
Making the timeout to wait for a yellow cluster state configurable.

Expects to be configured in milliseconds, defaulting to 5000.

Fixes #593, #171.
Merge branch 'master' of github.com:Graylog2/graylog2-server