Calls and plugins

[davidraker]

This pull request introduces several improvements to the platform_driver agent, focusing on better agent shutdown handling, improved heartbeat logic, and some dependency cleanup. The key changes involve using a gevent event to signal agent shutdown, refactoring the heartbeat mechanism to be more responsive to agent stop events, and removing an unnecessary installation step from setup.py.

Agent shutdown and heartbeat improvements:

• Added a _stop_agent event to the agent and a @Core.receiver('onstop') handler to set this event when the agent is stopping, enabling coordinated and graceful shutdown of greenlets. [1] [2]
• Updated the heart_beat method to run in a loop, checking for the _stop_agent event and sleeping dynamically based on the number of remotes. This ensures heartbeats stop promptly when the agent is stopped and distributes the heartbeat interval across remotes.
• Changed the heartbeat greenlet to use gevent.spawn instead of self.core.periodic, giving more control over the heartbeat loop and its termination.

Dependency and import updates:

• Added import of Event from gevent.event to support the new shutdown mechanism.
• Updated imports to include Core from the appropriate vip.agent module for both client and platform contexts, enabling the use of the @Core.receiver decorator. [1] [2]

Setup script cleanup:

• Removed the installation of vdrv from setup.py, streamlining the setup process.