Improve READ and change internal structure

• Improve the README
• Change the internal structure

1.2.0

• Make the trailing ; at the end of the import instructions optional
• Make the task compatible with the chained state feature

Only support PHP >= 7.1.0

Merge pull request #5 from elephfront/php71

Supports only PHP >= 7.1.0

Update documentation

1.0.1

Add codecov shield

1.0.0

Rewrite a sentence in the README.md file