ACCUMULO-2905 start multiple MinCs, starting with the largest

ACCUMULO-2905 updates based on [~elserj]'s review

ACCUMULO-2905 improved custom map

ACCUMULO-2905 more review feedback, formatted

ACCUMULO-2905 schedule fewer idle compactions

ACCUMULO-2905 improve javadocs based on rb comments

Conflicts:

	server/src/main/java/org/apache/accumulo/server/tabletserver/LargestFirstMemoryManager.java
Merge branch '1.5.2-SNAPSHOT' into 1.6.1-SNAPSHOT

Conflicts:
	server/base/src/main/java/org/apache/accumulo/server/tabletserver/LargestFirstMemoryManager.java