Get test coverage back to 100% of lines of code #187

Name                      Stmts   Miss  Cover   Missing
-------------------------------------------------------
src/celpy/__init__.py        68      0   100%
src/celpy/__main__.py       186      0   100%
src/celpy/adapter.py         50      0   100%
src/celpy/c7nlib.py         299      0   100%
src/celpy/celparser.py      204      0   100%
src/celpy/celtypes.py       603     10    98%   338, 404-408, 853, 943, 1378-1379
src/celpy/evaluation.py    1228      5    99%   295, 297, 344, 346, 1564
src/xlate/__init__.py         0      0   100%
src/xlate/c7n_to_cel.py     390      0   100%
-------------------------------------------------------
TOTAL                      3028     15    99%