Logging performance optimizations:
* Fixed custom Jetty logger to caches isDebugEnabled
* Changed LogbackService to cache isDebugEnabled
* Added isDebugEnabled check before toString() in GCResistantCache

Only add security filter if there are security rules
Merge pull request #2348 from rickardoberg/optimizedlogging4

Optimize logging and HTTP filter
Merge branch '1.9-maint' into 2.0-merge-1.9

Conflicts:
	community/server/src/main/java/org/neo4j/server/logging/JettyLoggerAdapter.java
	community/server/src/main/java/org/neo4j/server/web/Jetty6WebServer.java
	enterprise/ha/src/main/java/org/neo4j/kernel/impl/cache/GCResistantCache.java
Merge pull request #2375 from chrisvest/2.0-merge-1.9

2.0 merge 1.9