Move sshpublisher require into the rake tasks that use it so ruby 1.9 and macruby don't need the rake gem installed

If average value from DB is 0, make sure to convert it to a 0.0 float before calling #to_d on it [#1346 state:resolved]
Signed-off-by: NJoshua Peek <josh@joshpeek.com>

Simplify dispatcher callbacks to eliminate unnecessary stale thread purging. [Nick Sieger, Pratik Naik]
Signed-off-by: NPratik Naik <pratiknaik@gmail.com>

undef abstract methods instead of raising NotImplementedError. Still need the definitions for rdoc though.