Column name escape fix

Encountered an error when upgrading our cluster to 2.0 (obviously this gem doesn't current support that version)
when escaping column names.
Currently statement generates the following:
SELECT * FROM my_column_family WHERE 'my_column' = 1;
Cassandra 2.0 chokes on this it doesn't like the column name being escaped it needs to generate
SELECT * FROM my_column_family WHERE my_column = 1;

This is a quick and dirty fix, I'm not sure where else people are passing in symbols for strings.