Slave Permission Roles and Macro Extensions for roles

Hello, 

Changes summary:
* Individual configuration of roles for the Jenkins slaves
* Macro support for roles with extension points (users - todo)
 - Macro allows to implement specific handler for "hasPermission" check
 - Macro supports parameterization an multiple invocation (via "index" stub)
 - Demo: “BuildableJob macro” – Applies rule to buildable jobs only
* List of available macros

Best regards,
Oleg Nenashev

Several screenshots
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Top-level configuration page
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![top-level-config](https://f.cloud.github.com/assets/3000480/642490/0bfbace0-d35e-11e2-91af-4984fd78557a.png)

Macro usage + slave roles
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![manage-roles](https://f.cloud.github.com/assets/3000480/642491/1208f8c2-d35e-11e2-9acb-933ef31b13cd.png)

List of available macros
--------------
![macro-list](https://f.cloud.github.com/assets/3000480/642492/13ba351e-d35e-11e2-9402-a3c7d138f219.png)