add scale image test cases

add convert package testdata

refactor the convert package

add Example

Remove windows build

Add Converalls Badge

Update travis ci config file to support converalls

Add Cover badge

Test sub packages

Add test case cover

Add godoc badge

Add if colored the char test

Add ascii package test cases

Add ascii package test case

Update the example

Add testify package for testing

Fixed a slice allocate issue

Update README.md

fixed the go lint issue

Rewrite the go docs