Fix assertion error in ALTER TYPE RENAME

patch by mstepura & slebresn; reviewed by mstepura & slebresne for CASSANDRA-6705
Merge branch 'cassandra-2.1' into trunk
Scrub should not always clear out repaired status.

Patch by marcuse, reviewed by jbellis for CASSANDRA-5351
Merge branch 'cassandra-2.1' into trunk