Option to save the API creds

[vivsing4]

Having an option to save the API creds will help as the tool currently asks to feed the API creds everytime it is re-run.
Probably, have api_creds.conf file and give user and option to save the creds in it.
If the api_creds.conf is not found by the tool then prompt for entering creds to be provided.

[mafranks]

This is already available. Check #2 in the API Credentials section of the README