Move embedder, middleware, and head parameters to framework agnostic modules. (#45)

Part of #28

tutorials/0. Quick Start Guide.ipynb

@@ -134,7 +134,7 @@
     "from rl_coach.environments.gym_environment import GymVectorEnvironment\n",
     "from rl_coach.graph_managers.basic_rl_graph_manager import BasicRLGraphManager\n",
     "from rl_coach.graph_managers.graph_manager import SimpleSchedule\n",
-    "from rl_coach.architectures.tensorflow_components.embedders.embedder import InputEmbedderParameters\n",
+    "from rl_coach.architectures.embedder_parameters import InputEmbedderParameters\n",
     "\n",
     "# define the environment parameters\n",
     "bit_length = 10\n",

tutorials/3. Implementing a Hierarchical RL Graph.ipynb

@@ -162,9 +162,9 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from rl_coach.architectures.tensorflow_components.architecture import Dense\n",
+    "from rl_coach.architectures.tensorflow_components.layers import Dense\n",
     "from rl_coach.base_parameters import VisualizationParameters, EmbeddingMergerType, EmbedderScheme\n",
-    "from rl_coach.architectures.tensorflow_components.embedders.embedder import InputEmbedderParameters\n",
+    "from rl_coach.architectures.embedder_parameters import InputEmbedderParameters\n",
     "from rl_coach.memories.episodic.episodic_hindsight_experience_replay import HindsightGoalSelectionMethod, \\\n",
     "    EpisodicHindsightExperienceReplayParameters\n",
     "from rl_coach.memories.episodic.episodic_hrl_hindsight_experience_replay import \\\n",