[relaxed-caps-plugin] Invoke next() callback after modifying the capabilities

[sudharsan-selvaraj]

When the relaxed-caps plugin is used along with any other plugins, hande method present in other activated plugins is not invoked by appium.

Instead of creating a new session directly from the plugin, invoke next method so that other plugins will also get notified about the new session.

Scenario
Start appium server and load relaxed-caps and appium-device-farm plugin together. Now when new session is requested from the client, device-farm plugin will never be notified, since the relaxed caps plugin will handle the request and the next function is not being called. So this will block the users from trying out other plugins without updating their appium client version.

[jlipps]

OK, thanks for the report