Requirements cache interface

[richtja]

Is your feature request related to a problem? Please describe. Right now, the requirements cache is hidden inside avocado test process and user doesn't have any control over it. The main problem with this is, that if the data in cache doesn't correspond with the real state in the environment, the avocado won't work properly. In such situation, the only way how the user can fix avocado is to remove the requirement cache file, which is not very user-friendly approach.

Describe the solution you'd like Avocado provides vmimage cache interface. With this interface, user can list the cache and make updates. I would like to have similar interface for requirements cache. With this interface, the user will be able to list all the requirements stored in cache and remove those which doesn't respect the current environment.

Describe alternatives you've considered We can only create small script for removing the whole requirement cache. It will fix the problem with requirements cache, but it won't be so effective in situations when you have hundreds of entries, and you need to remove only one.