Future-proof inter-major-version schema migrations

patch by Aleksey Yeschenko; reviewed by Jonathan Ellis for
CASSANDRA-5845
Better exception msg for invalid CLUSTRING ORDER
add CqlPagingRecordReader support for ReversedType in Thrift table
patch by Alex Liu; reviewed by jbellis for CASSANDRA-5718
catch all Throwables, not just Exceptions
Merge branch 'cassandra-1.1' into cassandra-1.2
add --migrate optionto sstableupgrade and sstablescrub
patch by Tyler Hobbs; reviewed by Jeremiah Jordan for CASSANDRA-5831
fix potential overflow in extimatedKeys
Make SS look at the right piece for expire time.
Patch by brandonwilliams reviewed by jasobrown for CASSANDRA-5857
Correctly validate sparse composite cells
patch by Tyler Hobbs; reviewed by jbellis for CASSANDRA-5855
make scrubbing collection-aware
Add KeyCacheHitRate metric to CF metrics

patch by yukim; reviewed by jbellis for CASSANDRA-5868
migrate 1.1 schema_columnfamilies.key_alias column to key_aliases
patch by Alex Liu; reviewed by Tyler Hobbs for CASSANDRA-5800
Correct timestamp formatting in CQL3 doc
Remove the vestiges of default_{read,write}_consistency
CASSANDRA-5800 follow-up

patch by Aleksey Yeschenko; reviewed by Tyler Hobbs for CASSANDRA-5800
make sure to release recently added CF metric
Migrate key_alias->key_aliases on every schema migration (1.2)

Another follow-up to 5800
Skip auth setup if AllowAllAuthenticator is used
Authorizer+authenticator configuration sanity check
cqlsh: add support for multiline comments

patch by Aleksey Yeschenko; reviewed by Brandon Williams for
CASSANDRA-5798