using pytest for tests
added exemple file for tracking parcel
refactoring : creating a tracker class // not tested
typo
fixed class modification issues => self. problems
changed files names
typo
__all__ in __init__.py
changed typo in dir name
error from last commit
fixed flake8 for main.py
fixed flake8 for main.py
Revert "fixed flake8 for main.py"

This reverts commit 38bb58ef8f420bfc3a09d557d458337e53e56f4c.
fixed lint error
load requirements from requirements.txt
added pytest support in setup.py
test configuration
modified setup to support py.test
delete main in track_a_parcel.py
moved executable code