Create CLI script for generator

[rmariuzzo]

Currently we have a single NPM script for data generation purposes. However no script files exists. We would like to create a script files that replace the data generation process.

Tasks:

• Create a script file at: src/server/scripts/generate-data.js.
• Follow this guide to add the proper shebang directive and setup permissions only. Do not add a bin entry.
• The script file should support a --only option and only one of two values are accepted: users or repos. When that CLI option is specified, then only the specified set will be generated.
• Replace the current single NPM script (generate, scrape:users and scrape:repos) with one script: generate-data which will execute our new cli script defined at: src/server/scripts/generate-data.js.

[jouderianjr]

Hey, I can do this 💃

[rmariuzzo]

All yours mate! Take in account we are using Node 8+.