Separate mlflow deps

Closes #91 (closed)

dan/manager/training.py

@@ -19,16 +19,13 @@ from tqdm import tqdm
 
 from dan.manager.metrics import MetricManager
 from dan.manager.ocr import OCRDatasetManager
+from dan.mlflow import MLFLOW_AVAILABLE, logging_metrics, logging_tags_metrics
 from dan.ocr.utils import LM_ind_to_str
 from dan.schedulers import DropoutScheduler
 
-try:
+if MLFLOW_AVAILABLE:
     import mlflow
 
-    from dan.mlflow import logging_metrics, logging_tags_metrics
-except ImportError:
-    pass
-
 
 class GenericTrainingManager:
     def __init__(self, params):