Adding parallelism to AMQP producer and consumers.

(cherry picked from commit 0a55cafe48c63947a6616ad5f0a40c5021c3266c)
Moving ring_size configuration parameter to shared base configuration.

(cherry picked from commit 3cc7056f52c38624f3814f241cbe7db5f2a36222)
(cherry picked from commit 5e4b35ac33d41bcc68a9288b95ab737f519a47af)

Conflicts:
	graylog2-radio/src/main/java/org/graylog2/radio/Configuration.java
	graylog2-server/src/main/java/org/graylog2/Configuration.java
Introducting parallelism for periodical workers.

(cherry picked from commit 594949e9090f3063c8edd93e13d2bdd76f1b5583)
(cherry picked from commit 5046f8448d358e138fe68c7a000b37a857ae590c)
Adding default parallelism level of 1 to Periodicals.

(cherry picked from commit 775a711e36115bff8025a4871d39484b5b3e182b)
(cherry picked from commit ca784318ce0fbd90d7be1492a215931f542f1abc)
Correcting minor merge errors.