Refactor delete method.
added event publisher function for repository.
scaladoc & test
Merge pull request #14 from sisioh/feature/for_refactor_delete_method

Repository#deleteメソッドもResultWithEntityを返すように修正。
added support for sonatype repos.
add configutaion for pgp
Merge branch 'release/v0.1.20' into develop

Conflicts:
	project/Build.scala
v0.1.21
Merge branch 'release/v0.1.21'