Adds the importutil module that allows targetting a specific source RPM
file and importing and tagging. It aims to keep the same structure of
git.centos.org.
Other changes:
* constants.py: New constants added for git and rpm
* error.py: New git and rpm error classes added
* fileutil.py:
* Add filter_files_inverse (matches everything but the filter)
* Add get_magic_file (returns magic data from a file)
* Add get_magic_content (returns magic data from data/content)
* generic.py: Add safe_encoding to return a urlquote string
* processor.py:
* Add run_proc_foreground_shell to support shell calls
* Add run_proc_no_output_shell to support shell calls
* rpmutil.py:
* get_rpm_header now supports verify_signature parameter (default
false). If set to true and key is not available, raises exception.
* Add verify_rpm_signature, which allows local rpm verification
without ingesting the whole header into a usable object.
* Add add_rpm_key, which enables a user to add a key to the rpm
keyring.
