HBase-799 Created an error in util.migration.v5.HColumnDescriptor

The patch for HBASE-799 accidentally introduced an error in org.apache.hadoop.hbase.util.migration.v5.HColumnDescriptor. Line 345 of this file is currently:

this.name = Bytes.readByteArray(in);

This should be replaced by the following three lines, which were accidentally replaced by the HBASE-799 patch:

Text t = new Text();
t.readFields(in);
this.name = t.getBytes();

So, to summarize, line 345 of util.migration.v5.HColumnDescriptor should be replaced by the above 3 lines.