Metrics. Parameter standardization - all parameters are passed to __init__ and process as kwargs

[rfaulkner]

Method signatures in all metric classes should be:

class M(UserMetric):
    def __init__(self, **kwargs):
            ...
    def process(self, user_handle, **kwargs):
            ...

[rfaulkner]

implemented. https://github.com/rfaulkner/E3_analysis/commit/08abfff902037720ebb813c748a566e85a461fcd