handle ansi styled prefix

followup to 0968122686180d01e1c9aca26527d7a465b28e05

before it didn't detect the end of the string correctly when it ended in an ansi escape.

also make sure the inserted `:` is inserted inside any ansi escape code.
Merge pull request #162 from sindresorhus/handle-colors-prefix

handle ansi styled prefix
0.7.3
Add inquirer.createPromptModule

This method allow the creation of self contained prompt function. This
mean prompts defined on each instances of a prompt module won't pollute
the scope of another.