New CLI Parameter for Rows per Insert

[ahmad-511]

#30 This is my attempt to specify how many rows to add per one insert statement
Syntax:
npm start YourFileName [batch size]

for example, to generate 100 rows per insert using the ExampleTable.csv file
npm start ExampleTable 100

[gitdagray]

Nice Ahmad! Consider updating the README for this feature, too. 🎉

Fixes #30