Change the way debian_role is obtained

[skhakimov]

Currently a project's role (e.g. Shared Library, Program, Application Data, etc.) is obtained from https://packages.debian.org/wheezy/. For example, to get a project's 'role' and 'implemented in', one goes to https://packages.debian.org/wheezy/bash and sees that it is a Program, implemented in C.

An alternative and easier way to get this information is from the apt_cache_dumpavail.txt file which is already being used in the repo.