SampleRatio class not working for sample sizes below 1000

[oleolegka]

tea-tasting/src/tea_tasting/metrics/proportion.py

Line 153 in e80d704

pvalue = scipy.stats.binomtest(k=k, n=n, p=p).pvalue

scipy.stats.binomtest requires that both k and n must be int, but

 k = aggr[treatment].count()
 n = k + aggr[control].count()

returns float

[e10v]

Fixed in #73. I'll close the issue after releasing the next version.