v0.9.0

Apply changes to github.com/pkg/errors package to make it compatible with the new errors of version go 1.13.

Furthermore if you use a previous version than go 1.13 the library was be compiled using golang.org/x/xerrors package.

The change have been aplying about Wrap, Wrapf and Cause, on the other hand now the package have the methods As and Is, more information on project godoc