spec: lot of fixes

* Corrected url of source archive.
* Require openlmi-providers which owns /etc/openlmi directory.
* Own /etc/openlmi/scripts directory.
* Require python-docopt on build.
* Do not make configs out of completion scripts.
* Removed _isa macros.
* Require at least openlmi-tools 0.8. Use the right download link from
  github (according to fedora pkg guidelines).
* Made subpackages dependent on the version of openlmi-scripts, not on
  their own version.
support newer versions of lmi shell (0.8 and above)

Hostname property of LMIConnection has been renamed to uri.
let's require newer shells

Require at least version of openlmi-tools 0.8.
add utility function get_computer_system()

It caches instance of computer system per each host/namespace. It tries
to obtain instance of the preffered class which can be configured in
configuration file and currently defaults to PG_ComputerSystem. If such
class does not exist, CIM_ComputerSystem is enumerated instead.
bumped version to 0.2.4

Updated changelog.
software: support and require new lmi shell (v0.9)

Use get_computer_system() instead of hardcoded ComputerSystem class.
service: support newer lmi shell version (v0.8)

Use get_computer_system() instead of hardcoded ComputerSystem class.
logicalfile: do not hardcode ComputerSystem class name
hardware: do not hardcode ComputerSystem class name