Right now the code looks weird because the defaults
of a pipe are far away of the implementation of the pipe.
the intend of this PR is to bring them closer by having a
Defaulter interface.
I also renamed the Pipe interface to Piper, and removed
the Description method in favor for fmt.Stringer.
The field is optional. When set to true, files in archive are wrapped
in a directory, which has the same name as the archive itself.
Tests have also been extended to cover this.
Closes#251
See #243.
Upload binaries directly instead of creating archive.
This option, however currently doesn't work together with brew and fpm
since they both require archived artifacts.
