Merge ColumnFamily, ISortedColumns.  Add EmptyColumns and UnsortedColumns; clean up TMBSC, ABSC, and ASC
patch by jbellis; reviewed by Carl Yeksigian for CASSANDRA-5403
use guava's Iterators class and emptyIterator
with HashCodeBuilder use toHashCode() not hashCode()
fix duplicate ip address error message
Merge remote-tracking branch 'apache/trunk' into cie

Conflicts:
	src/java/org/apache/cassandra/locator/YamlFileNetworkTopologySnitch.java
	src/java/org/apache/cassandra/tracing/TraceState.java
	src/java/org/apache/cassandra/tracing/Tracing.java
Rename CIE to Endpoint
More renames