Bumping version to 0.91.3
Merge tag '0.91.3' into 0.91+perfFixes

Conflicts:
	graylog2-inputs/pom.xml
	graylog2-plugin-interfaces/pom.xml
	graylog2-radio/pom.xml
	graylog2-rest-client/pom.xml
	graylog2-rest-routes/pom.xml
	graylog2-server/pom.xml
	graylog2-shared/pom.xml
	pom.xml