Merge pull request #9 from utahta/add-test-go-1-15

add test for go-1.15 to CI

Use github.com/lestrrat-go/strftime

Add tests

Update README.md

Add codecov

Update doc

Merge pull request #1 from utahta/change_package_name

Change package name

Add WithSymlink

improve debug log

Make struct public

Add WithInit option