Track min/max timestamps and maxLocalDeletionTime correctly

Patch by marcuse; reviewed by tjake for CASSANDRA-7969
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	src/java/org/apache/cassandra/db/ColumnFamily.java
	src/java/org/apache/cassandra/db/compaction/LazilyCompactedRow.java
	src/java/org/apache/cassandra/io/sstable/SSTableWriter.java
Merge branch 'cassandra-2.1' into trunk

Conflicts:
	test/unit/org/apache/cassandra/db/RangeTombstoneTest.java