Adding new SPEC file SPECS/graylog2-radio.spec with related sources.

The source file SOURCES/init.d-graylog2-radio is a standard INIT
script, copied from the graylog2-server script with the variable
names changed and replacing server with radio.

With the default variables set in SOURCES/init.d-graylog2-radio
the new file SOURCES/sysconfig-graylog2-radio enables the users
to set custom settings for the service. Like configuration file,
PID file path, additional java opts to name a few. The only
significant setting in this file is setting the java system
property log4j.configuration in the ADDITIONAL_JAVA_OPTS var.

Adding a simple log4j configuration SOURCES/log4j-graylog2-radio.xml
to save all information, INFO and greater, to the log file
/var/log/graylog2/radio.log and rotate it daily.
Removing plugin directory installation in graylog2-radio.spec

https://github.com/corey-hammerton/graylog2-rpms/issues/3

Since there is no plugin requirement for the graylog2-radio package
the creation and installation of the plugin dir was not supposed
to be present. Since this file is a modified copy of
graylog2-server.spec file this is collateral damage.

Building the RPM now succeeds.