Extending plugins functionality (two extra functions)

[michalmanko]

Now plugin can have two extra functions:

• initializeDb() - a Databank object can be passed to a plugin directly
• configureApp() - this method is executed much earlier than initializeApp() and allows to configure the app (e.g. add a middleware)

[strugee]

@michalmanko thanks for sending this PR.

Unfortunately I'm uncomfortable merging this, at least at the present time. Plugins aren't really supported right now - Evan has indicated that they may go away in a future pump.io version (see #588 where they were originally implemented), and I'm inclined to rip out the code until we're ready to support them. If we end up doing that, merging this doesn't really make a whole lot of sense.

To elaborate, right now we have a lot of work ahead of us upgrading core dependencies - see for example the work going on in the express-3.x branch. The way that plugins are implemented, the libraries used internally by the application essentially become part of the public plugin API. If we choose to officially support plugins, each dependency upgrade would trigger a bump of the major version number of pump.io. Otherwise, we wouldn't be respecting semver by causing potential plugin breakage.

In any case, I'll bring this up at the next monthly meeting.

[strugee]

Note also that plugins are currently undocumented.

[strugee]

Hey @michalmanko - still interested in getting this into pump.io core?

We decided during the meeting before last not to drop plugin functionality just yet (although we do plan to eventually replace it with something that doesn't have the problems I've described above). Hence, I have no issues merging this PR - sorry I forgot about it until now!