[JENKINS-20398] Job Property to define projects that can copy artifacts

This is an implementation for [JENKINS-20398] (https://issues.jenkins-ci.org/browse/JENKINS-20398), another approach for [JENKINS-14999] (https://issues.jenkins-ci.org/browse/JENKINS-14999) "Copy Artifact plugin: Unable to find project for artifact copy when using a build parameter".

With #26, we can now control permissions to copy artifacts by specifying authorization of copying project.
But that requires following steps:
1. setting up an user account to control permissions.
2. allow that account to access the project who creates artifacts.
3. configure the project who copy artifacts to run with authorization of that account.

Generally it is bothering and a mistaken configuration can cause security issue.

With this feature, users can simply define projects who can copy artifacts from that projects like this:
![jenkins-20398-snapshot](https://f.cloud.github.com/assets/3115961/1749911/90c37a2e-6554-11e3-8506-62d4620ab388.png)