RFR: Extend the repository configuration syntax

[Robin Westberg via github.com]

Hi all,

Please review this change that extends the BotRunner configuration parsing of repository names. Previously, every repository had to be described one time for each host/credential set it was to be used with. Now it is allowed to specify this directly as a string of the form `<host definition name>/<actual repository name>`. Additionally, a ref name can optionally be appended of the form `:<ref name>` at the end of the string.

Best regards,
Robin

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Commits:
 - 78bc64f4:	Extend the repository configuration syntax, allow fetching an embedded ref name

Pull request:
https://git.openjdk.java.net/skara/pull/116

Webrev:
https://webrevs.openjdk.java.net/skara/116/webrev.00

Patch:
https://git.openjdk.java.net/skara/pull/116.diff

Fetch command:
git fetch https://git.openjdk.java.net/skara pull/116/head:pull/116