Add component edit/KeyValue

Add edit component of KeyValue to react-components package.

• Should represent object (json), where the key is string and value is string (if can implement that value can be other types like number / date for example it will be great).
• Should be able to add key value, and then see it in a list of key-values. each row of key value is also editable, and can be removed.
• Add also an .md file similar to other components