Anomaly call likelihood

pass correct values to `anomaly_likelihood`, enable `Anomaly.MODE_LIKELIHOOD` 
and provide test (serving as an example how to use the Anomaly class)

Fixes #967 
still lots of places with spaces around `=` in assignment statement. Here you could use parentheses instead of backslash for line continuation. See backslash comments here:
http://legacy.python.org/dev/peps/pep-0008/#maximum-line-length