Update logback to 1.2.9

logback-parent isn't really a bom but instead includes other unrelated
depenedncies like mockito and jodatime, and so I am just adding the
individual logback and slf4j dependencies themselves. Also add
slf4j-simple in dependencyManagement for the various test dependencies
we have on it.

http-api/pom.xml

@@ -68,7 +68,6 @@
 		<dependency>
 			<groupId>org.slf4j</groupId>
 			<artifactId>slf4j-simple</artifactId>
-			<version>1.7.12</version>
 			<scope>test</scope>
 		</dependency>
 		<dependency>