Move FoodCollector to gail_config and remove offline_bc_config.yaml (#3170)

* Move FoodCollector to gail_config

config/gail_config.yaml

     max_steps: 5.0e5
     num_epoch: 3
     behavioral_cloning:
-        demo_path: ./demos/ExpertPyramid.demo
+        demo_path: demos/ExpertPyramid.demo
         strength: 0.5
         steps: 10000
     reward_signals:
     num_layers: 3
     hidden_units: 512
     behavioral_cloning:
-        demo_path: ./demos/ExpertCrawlerSta.demo
+        demo_path: demos/ExpertCrawlerSta.demo
         strength: 0.5
         steps: 5000
     reward_signals:
             gamma: 0.99
             encoding_size: 128
             demo_path: demos/ExpertHallway.demo
+
+FoodCollector:
+    batch_size: 64
+    summary_freq: 1000
+    max_steps: 5.0e4
+    use_recurrent: false
+    hidden_units: 128
+    learning_rate: 3.0e-4
+    num_layers: 2
+    sequence_length: 32
+    reward_signals:
+        gail:
+            strength: 0.1
+            gamma: 0.99
+            encoding_size: 128
+            demo_path: demos/ExpertFood.demo
+    behavioral_cloning:
+        demo_path: demos/ExpertFood.demo
+        strength: 1.0
+        steps: 0

config/offline_bc_config.yaml

-default:
-    trainer: offline_bc
-    batch_size: 64
-    summary_freq: 1000
-    max_steps: 5.0e4
-    batches_per_epoch: 10
-    use_recurrent: false
-    hidden_units: 128
-    learning_rate: 3.0e-4
-    num_layers: 2
-    sequence_length: 32
-    memory_size: 256
-    # Change the path here to point to your demo files
-    demo_path: ./UnitySDK/Assets/Demonstrations/Your_Demo_File.demo
-
-FoodCollector:
-    trainer: offline_bc
-    batch_size: 64
-    summary_freq: 1000
-    max_steps: 5.0e4
-    batches_per_epoch: 10
-    use_recurrent: false
-    hidden_units: 128
-    learning_rate: 3.0e-4
-    num_layers: 2
-    sequence_length: 32
-    memory_size: 256
-    demo_path: ./demos/ExpertFood.demo
-
-Hallway:
-    trainer: offline_bc
-    max_steps: 5.0e5
-    num_epoch: 5
-    batch_size: 64
-    batches_per_epoch: 5
-    num_layers: 2
-    hidden_units: 128
-    use_recurrent: true
-    memory_size: 256
-    sequence_length: 32
-    demo_path: ./demos/ExpertHallway.demo
-