cqlsh: Fix IPv6 Support

This commit upgrades the bundled datastax/python-driver to
ad2f61f8655.

Patch by Tyler Hobbs; reviewed by Philip Thompson for CASSANDRA-7988
Increase nodetool Xmx
patch by Nikolai Grigoriev; reviewed by jbellis for CASSANDRA-7956
merge from 2.0
Merge remote-tracking branch 'origin/cassandra-2.1' into cassandra-2.1
Fix possible overflow while sorting CL segments for replay
patch by Oleg Anastasyev; reviewed by jbellis for CASSANDRA-7992
merge from 2.0
CHANGES
Merge branch 'cassandra-2.0' into cassandra-2.1
Better validation of collection values

patch by slebresne; reviewed by thobbs for CASSANDRA-7833
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:
	CHANGES.txt
	src/java/org/apache/cassandra/serializers/ListSerializer.java
Make native server start block until properly bound

patch by slebresne; reviewed by xedin for CASSANDRA-7885
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
Notify whenever we replace an SSTableReader

Patch by marcuse; reviewed by yukim for CASSANDRA-8034
Fix potential exception with ReversedType in DynamicCompositeType

patch by timw; reviewed by slebresne for CASSANDRA-7898
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
Release references to compacted overlapping sstables during compaction

Patch by benedict; reviewed by marcuse for CASSANDRA-7819
fix build
Fix AssertionError in RangeTombstoneList diff

Patch by Philo Yang and Oleg Anastasyev; reviewed by Tyler Hobbs for
CASSANDRA-8013
Fix snapshot repair error on indexed tables

patch by yukim; reviewed by jbellis for CASSANDRA-8020