Plugin for filters

[rajaramsrinivas]

The current version allows for plugins to be separate methods in analyze_modules.py going by the name analyze_. This attribute should be added in two new locations:

1. In models.py for db field name
2. in tasks in list ANALYSIS_TYPE of scripts/tasks.py

Since api/feed.py already queries for all attributes, by default, only UI will need to be modified from here.

Please review and approve pull request if you deem the changes fit.

[rahulbot]

This seems like a good first step, but doesn't really do a plugin pattern. You're using a whitelist and then a naming convention to discover analysis methods. That's better than what we've got now, but from an architecture point of view I think a more plug-in oriented approach would involve some mechanism for registering analytic plug-ins with gobo from individual modules. I merge this, because it is an improvement, but lets discuss a more robust solution on #32.