Refactor package management

* Yyoom installs packages using rpm name and version specificators
  now instead of rpm name and python requirement.
* Yyoom searches for packages during transaction execution.
* Yyoom switch '--skip-missing' added to specify whether raise
  exception when unable to find the desired package or to add
  these packages to result.
* Smithy script corrected to work with yyoom executable instead
  of yumfind.
* Yumfind script removed.

Implements: blueprint refactor-package-management
Change-Id: Id67d8284390384d526ce3de8ec2d66453975deea