Actions are no longer hard-coded client-side, and custom actions no

longer require subclassing RB.LicenseView.
A registered action can now provide extra_data, which can be handled

specially by a RB.LicenseView subclass, and call_args, which will be

included in an action call back to the License Provider when clicked.
License action handlers can provide new license action updates, just

like a Check Update request, by returning license_infos in the

response. It can also redirect to a URL by providing redirect_urls.
This makes it possible for an action to begin a more involved

license-related flow kicked off by the License Provider and going

through other servers or URLs.
Since actions are more dynamic now, we no longer hard-code the Manage

License and Upload License actions within RB.LicenseView. Instead,

BaseLicenseProvider.get_license_actions() now registers these by

default, and subclasses can override them or reposition them.
Since the Upload License action is special, RB.LicenseView still needs

to handle it specially. This is now done through

RB.LicenseView.actionBuilders, which is a mapping of action IDs to

custom builder functions. The Upload License handler is registered in

this mapping.

Unit tests pass.
Registered some custom actions and verified that clicking them triggered

a call handled the License Provider. Also verified that the license_infos

and redirect_url results worked.