update SpringBoot to 2.1.9

Also remove direct dependencies to log4j-api and log4j-core where
possible. log4j-slf4j-impl is enough in many cases.

block-storage/build.gradle

@@ -5,7 +5,7 @@ dependencies {
 	compile project(':file-utils')
 	compile project(':pdb-utils')
 	
-	compile lib_log4j2_core
+	
 	compile lib_log4j2_slf4j_impl
     compile lib_primitive_collections
 }