add creadential feature to manage credentials at job location

[pserranoa]

I make some changes to your plugin and your jenkins utils to avoid manage credentials located under job. You should use a new parameter "jobpath" to indicate the location of the job.

Ex. resource "jenkins_username_credential" "cheduller01" { identifier = "terraform_create_credential_dos" username = "admin" password = "xxxxxxxxxxxxxxxxxxxxxxxxxxx" jobpath = "Scheduller01" domain = "team01" description = "team01 - cheduller01" }

I send you the pull request of the package that manage jenkins too.

• Enabled the posibility to export variables to get the user and password of jenkins
• Enabled the posibility to create secret text credentials

[piotrjaromin]

Thanks for contributing!