Implementing pattern size-limited cache for RegexMatchers

Changing control flow for BlacklistFilter, so matching against blacklists does not end when LoadingCache throws exception
fix typo
add trace logging to track processed messages

to be able to debug single messages flowing through the system it is important to be able to trace every single message id at every single decision point.
you have to manually increase the log level to TRACE in org.graylog2.outputs and org.graylog2.buffers.processors to see the new out (warning: _very_ verbose)
manual sorting of extractors Graylog2/graylog2-web-interface#726
Merge branch '0.20' of github.com:Graylog2/graylog2-server into 0.20
allow loading of different radio transport types. #385
AMQP support for radio. #385
renamed Kafka radio input class (non-breaking) #385
AMQPInput #385
radio AMQP input #385
proper (re-)connection handing for AMQP inputs. fixes #385
set radio version to snapshot
set maven to snapshot versions
improve network trace logging

fixes #507
Merge branch '0.20'

also bump mvn version to 0.21.0-SNAPSHOT to disambiguate

Conflicts:
	graylog2-inputs/pom.xml
	graylog2-inputs/src/main/java/org/graylog2/inputs/gelf/gelf/GELFProcessor.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/gelf/http/GELFHttpPipelineFactory.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/gelf/tcp/GELFTCPPipelineFactory.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/gelf/udp/GELFUDPPipelineFactory.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/radio/RadioInput.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/raw/tcp/RawTCPPipelineFactory.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/raw/udp/RawUDPPipelineFactory.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/syslog/tcp/SyslogTCPPipelineFactory.java
	graylog2-inputs/src/main/java/org/graylog2/inputs/syslog/udp/SyslogUDPPipelineFactory.java
	graylog2-plugin-interfaces/pom.xml
	graylog2-plugin-interfaces/src/main/java/org/graylog2/plugin/inputs/MessageInput.java
	graylog2-radio/pom.xml
	graylog2-radio/src/main/java/org/graylog2/radio/Configuration.java
	graylog2-radio/src/main/java/org/graylog2/radio/Main.java
	graylog2-radio/src/main/java/org/graylog2/radio/Radio.java
	graylog2-server/pom.xml
	graylog2-server/src/main/java/org/graylog2/Main.java
	graylog2-server/src/main/java/org/graylog2/buffers/processors/OutputBufferProcessor.java
	graylog2-server/src/main/java/org/graylog2/inputs/Input.java
	graylog2-server/src/main/java/org/graylog2/outputs/ElasticSearchOutput.java
	graylog2-shared/src/main/java/org/graylog2/shared/buffers/processors/ProcessBufferProcessor.java
	pom.xml