Fix CFMetaData#getColumnDefinitionFromColumnName()

patch by Sergio Bossa; reviewed by Aleksey Yeschenko for CASSANDRA-7047
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
	src/java/org/apache/cassandra/config/CFMetaData.java
Merge branch 'cassandra-2.1' into trunk