Remove keras package. (#132)

* Remove keras package. In issue #109, we decided to work toward a single framework API for now.

* Created tensorflow-framework/README.md and linked it from the main readme.

Author: deansher

README.md

@@ -24,19 +24,10 @@ The following describes the layout of the repository and its different artifacts
     TensorFlow and just want a thin layer to access the TensorFlow runtime from the JVM 
 
 * `tensorflow-framework`
-  * Complete but fairly primitive API for building and training neural networks with TensorFlow
-  * Intended audience: expert neural network developers who prefer to make explicit, detailed decisions 
-    about their models and training algorithms
-    
-* `tensorflow-keras` (early WIP; only defined in `dev` profile)
-  * Partially covers the framework API to allow simpler definition of models and training algorithms
-  * Intended to be familiar if you know the Python Keras API, but prioritizes clean, idiomatic Java 
-    over fidelity to Python
-  * Provides defaults based on common best practices
-  * Allows developers to selectively be more explicit by overriding defaults or dipping into the framework API
-  * Intended audience: neural network developers across the spectrum from beginner to expert who prefer to
-    rely mostly on best-practice defaults and then selectively fine-tune
-  
+  * Primary API for building and training neural networks with TensorFlow
+  * Intended audience: neural network developers
+  * For more information: [tensorflow-framework/README.md](tensorflow-framework/README.md)
+     
 * `ndarray`
   * Generic utility library for n-dimensional data I/O operations
   * Used by TensorFlow but does not depend on TensorFlow

pom.xml

@@ -119,19 +119,6 @@
   </dependencyManagement>
 
   <profiles>
-    <!--
-    Developing profile
-        The 'dev' profile is used for local development or PR compilation check only.
-        Here, we enable the `tensorflow-keras` module only under this profile, until
-        it is mature enough for being deployed and distributed for the end users.
-    -->
-    <profile>
-      <id>dev</id>
-      <modules>
-        <!-- Disabled while the library is still empty -->
-        <!--module>tensorflow-keras</module-->
-      </modules>
-    </profile>
     <!--
     Deploying profile
         Build the Javadoc when deploying

tensorflow-framework/README.md

@@ -0,0 +1,28 @@
+# Framework API
+
+This is the primary Java API for building and training neural networks with TensorFlow.
+This API deliberately mirrors the overall structure of Python Keras. However, it
+is intended as a comfortable, idiomatic Java API for developers who may or may not
+be familiar with Keras.
+
+This API is intended to provide convenient, sensible defaults, while still allowing you to 
+exercise fine control over the details of your model, training, and inference when necessary.
+
+More specifically, the following goals drive API evolution:
+
+* If either you know how to implement a model in the Python Keras API, or you are reimplementing an 
+  existing Python Keras model in Java, you should be able to cleanly and naturally follow the same 
+  high-level structure in the framework API.
+
+* Also, given some familiarity with patterns followed throughout the framework API, you should be 
+  able to easily translate every detail of a Python Keras implementation into the framework API.
+
+* However, the framework API is not intended to literally mimic the Python Keras API. Rather, it 
+  should expose the same capabilities in an API that feels natural and idiomatic to a Java 
+  programmer who does not know Keras. If we ever find ourselves unable to reconcile this goal with 
+  easy translation from Python Keras, we may split out a Keras layer.
+
+* Also, the framework API should support fine control over all aspects of modeling, training, and 
+  inference. Unlike with Python Keras, we want this to feel like staying in the same API rather 
+  than diving into a separate layer. But here again, if we are ever unable to reconcile this goal 
+  with easy translation from Python Keras, we may split the framework API into two layers.