added functionality for add/delete node(s)

[stephenranjit]

Hi, This tool is very useful for my team, Thank you!. I've added CLI interface for adding/deleting node(s).

1. Using a json file for bulk node creation: bin/jenkinscli node create_new_node -c <path to yaml file with Jenkins credentials>/login.yml --json <path to json file with a list of tmp machines>host-list.json
2. Create one node: jenkinscli node create_new_node -c login.yml --name tmppn0019648001.lab.in --credentials_id e7df46-278c-459d-8cfd-ec93b21a54 --labels test --executors 2
3. delete node command also has similar construct

login yaml file example config/login.yml.example tmp host list example : config/host-list.json

could you please review my code and accept the changes? Thanks again!

[stephenranjit]

eb045a5bed has all the changes you asked to be made. Please check when you find time. thanks again!