Should we load plugins when using multiple clients?

[BethanyBerkowitz]

See #1172 (comment)

Our browser and server clients have a factory() method to create a second instance of the client. This can be used if a project needs to report to multiple HB projects, for example.

However, when creating a new client, we don't include the plugins that were present in the initial client. This could be confusing because, for example, the original client will report uncaught errors and the clone will not because it doesn't have the uncaught exception plugin.

Our existing plugins for uncaught exception and unhandled rejection are not necessarily designed to be loaded in two separate clients -- if we decide we want to load the plugins in the secondary client(s), we should do some careful review of the code and testing to make sure that the plugins will function correctly.