Define different level of output message

[lenguyenthanh]

To make our app easy to use, we need to define and follow a structure level of output messages. I suggest we have 4 levels and their colors:

- Success - Green: Like: Cloned a repository success
- Info - White: To show information like: start to clone a repository
- Warning - Yellow : Some thing not right but still work
- Error - Red: Something went wrong, failed.

List of fixed commands:

• create_branch
• push

[snomos]

Sounds good. I suggest the yellow goes toward orange, otherwise it can be hard to differentiate from white.