Hourly and Daily rolling should use a single reducer + fix classpath issue

Hourly and Daily rolling should not use more than one reducer and they are currently relying on the default parameter to be correct.

<property>
<name>mapred.reduce.tasks</name>
<value>1</value>
<description>The default number of reduce tasks per job. Typically set
to a prime close to the number of available hosts. Ignored when
mapred.job.tracker is "local".
</description>
</property>

This should be forced within the Rolling class in order to avoid any issue.