epinions benchmark: 'rank' as the column name causes an issue in MySQL (fix included)

[arunmarathe]

Epinion benchmark's 'review' table has a column called 'rank'. It seems to be a reserved word in MySQL, and not permitted as a column name.

A solution is to backtick the column name viz. rank, but I believe a better solution is to simply rename the column to rank1.

I was able to both create the benchmark, and do a sample run with rank1 as the column name. I modified this file:

build/com/oltpbenchmark/benchmarks/epinions/ddls/epinions-ddl.sql

Thanks,
Arun