Ticket #2812: rpm vfs: add dependency version output.

This commit does some rpm extfs facelift and adds dependency version
output; since this shifts the semantics from "name" to "name and maybe
a version", the generated virtual file has been renamed either (REQUIRES
instead of REQUIRENAME, more in a line with PROVIDES).

It is esteemed that nothing worse than a passing surprise for some users
would happen while improving the overall usefulness.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '2812_rpm_requires_versions'

* 2812_rpm_requires_versions:
  Ticket #2812: rpm vfs: add dependency version output.