stress fail: when data_block_hash_table_util_ratio is 0 #214

Describe the bug
open error: Invalid argument: data_block_hash_table_util_ratio should be greater than 0 when data_block_index_type is set to kDataBlockBinaryAndHash

the python script that produces the cmd (tools/db_crashtest.py) for the stress tool can generate value 0 for data_block_hash_table_util_ratio when data_block_index_type is set to kDataBlockBinaryAndHash which is wrong.

fix by limiting range of data_block_hash_table_util_ratio from 0.01 to 1. (instead of 0 to 1)