Python: Moved bindings/python/elliptics to bindings/python/src. Added context to ExecResultEntry. Added address and error to all ResultEntries which are inherited from CallbackResultEntry. Added la, __str__ and __repr__ to Statistics. Fixed test_iterator.py and test_modern.py. Removed read_latest.py and range.py. Removed test.py (duplicates test_modern.py) and renamed test_modern.py to test.py.