Add column update delta histogram

Patch by Sankalp Kohli, review by jmckenzie for CASSANDRA-7979
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	src/java/org/apache/cassandra/db/AtomicSortedColumns.java
	src/java/org/apache/cassandra/db/ColumnFamilyStore.java
	src/java/org/apache/cassandra/db/Memtable.java
	src/java/org/apache/cassandra/metrics/ColumnFamilyMetrics.java
Add column update delta histogram (2.1)

Patch by Sankalp Kohli, review by jmckenzie for CASSANDRA-7979
Merge branch 'cassandra-2.1' into trunk

Conflicts:
	src/java/org/apache/cassandra/db/AtomicBTreeColumns.java
	src/java/org/apache/cassandra/db/Memtable.java
Fix non-text comparator col names in cql3 queries

Patch by Tyler Hobbs; reviewed by Aleksey Yeschenko for CASSANDRA-8178
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk

Conflicts:
	src/java/org/apache/cassandra/cql3/ColumnIdentifier.java
	src/java/org/apache/cassandra/cql3/Cql.g
	src/java/org/apache/cassandra/cql3/statements/SelectStatement.java
	src/java/org/apache/cassandra/cql3/statements/Selectable.java
	src/java/org/apache/cassandra/cql3/statements/Selection.java
Make cache serializers pluggable

patch by Blake Eggleston; reviewed by Aleksey Yeschenko for
CASSANDRA-8096
Merge branch 'cassandra-2.1' into trunk
honor the iterator.next() contract for exceptions
oops, fix tabs->spaces
Merge remote-tracking branch 'origin/trunk' into 7813-udf-keyspace

Conflicts:
	src/java/org/apache/cassandra/cql3/Cql.g
Merge branch '7813-udf-keyspace' into 8053-udaf-v2