ACCUMULO-3258 Make the dfs.datanode.synconclose check only fire once and ensure logging is properly set up.

Fixed up some initialization code so that logging is actually one of the first things
that happens so log messages aren't thrown into the .out files (as was
normally the case).
Merge branch '1.6'

Conflicts:
	server/base/src/main/java/org/apache/accumulo/server/Accumulo.java
	server/gc/src/main/java/org/apache/accumulo/gc/SimpleGarbageCollector.java
	server/master/src/main/java/org/apache/accumulo/master/Master.java
	server/monitor/src/main/java/org/apache/accumulo/monitor/Monitor.java
	server/tserver/src/main/java/org/apache/accumulo/tserver/TabletServer.java
ACCUMULO-3258 Consolidate "tserver" into application variable
Merge branch '1.6'