Batch insert into table (11% faster)

[vsdutka]

No description provided.

[coveralls]

Coverage decreased (-1.9%) to 85.345% when pulling 23f584e on vsdutka:master into 3acefb2 on casbin:master.

[hsluoyz]

Hi @vsdutka ,

Good job for improving the performance by 11%! It would be better if you can provide the performance example together in the test like func BenchmarkXxx(*testing.B)