pep8: fixed test_plugins.py file
implemented Command helper class (fix #33)
command: splits by lines single string command
command: does not add 'cd work_dir' to command lines
BuildArch and mandatory fields added(fix #36)(fix #38)
Implemented logging setup

Fixes #19
Fixed project building
logging: printing output also on screen
added logging to critical methods of components
(fix #37) + more pretty look for import page
Subpackages page UI works (moving files to sub-package)
Small red stars near labels, no highlighting for req. fields
Two buttons for import (fix #40)
Import text field changes during writing (fix #41)
More pretty highlighting of import
Subpackages page - removed tree children problem
Uncommented base classes methods
gitignore: added rpg.log
base: implemented compute_checksum method
f