added missing class1 file

mhcflurry/class1.py

+import pandas as pd
+
+from .mhc1_binding_predictor import Mhc1BindingPredictor
+
+def predict(alleles, peptides):
+    allele_dataframes = []
+    for allele in alleles:
+        model = Mhc1BindingPredictor(allele=allele)
+        df = model.predict_peptides(peptides)
+        allele_dataframes.append(df)
+    return pd.concat(allele_dataframes)