Update readme and make genetics module optional

PiperOrigin-RevId: 162570620

Author: Ryan Sepassi

README.md

@@ -23,8 +23,10 @@ send along a pull request to add your dataset or model.
 See [our contribution
 doc](CONTRIBUTING.md) for details and our [open
 issues](https://github.com/tensorflow/tensor2tensor/issues).
-And chat with us and other users on
-[Gitter](https://gitter.im/tensor2tensor/Lobby).
+You can chat with us and other users on
+[Gitter](https://gitter.im/tensor2tensor/Lobby) and please join our
+[Google Group](https://groups.google.com/forum/#!forum/tensor2tensor) to keep up
+with T2T announcements.
 
 Here is a one-command version that installs tensor2tensor, downloads the data,
 trains an English-German translation model, and lets you use it interactively:

tensor2tensor/data_generators/all_problems.py

@@ -21,12 +21,20 @@
 from tensor2tensor.data_generators import algorithmic
 from tensor2tensor.data_generators import algorithmic_math
 from tensor2tensor.data_generators import audio
-from tensor2tensor.data_generators import genetics
 from tensor2tensor.data_generators import image
 from tensor2tensor.data_generators import lm1b
 from tensor2tensor.data_generators import ptb
 from tensor2tensor.data_generators import snli
 from tensor2tensor.data_generators import wiki
 from tensor2tensor.data_generators import wmt
 from tensor2tensor.data_generators import wsj_parsing
+
+# Problem modules that require optional dependencies
+# pylint: disable=g-import-not-at-top
+try:
+  # Requires h5py
+  from tensor2tensor.data_generators import genetics
+except ImportError:
+  pass
+# pylint: enable=g-import-not-at-top
 # pylint: enable=unused-import