Fix baselines build (fails due to lack of mujoco in public baselines container) (#29)

* make nminibatces = min(nminibatches, nenv)

* clarify the usage of lstm policy, add an example and a test

* cleaned up example, added assert to the test

* remove nminibatches -> min(nminibatches, num_env)

* removed code snippet from the docstring, pointing to the file

* add _mujoco_present flag to skip the tests that require mujoco if mujoco is not present

* re-format skip message in test_doc_examples

* flake8 complaints

baselines/common/tests/test_doc_examples.py

@@ -1,3 +1,16 @@
+import pytest
+try:
+    import mujoco_py
+    _mujoco_present = True
+except BaseException:
+    mujoco_py = None
+    _mujoco_present = False
+
+
+@pytest.mark.skipif(
+    not _mujoco_present, 
+    reason='error loading mujoco - either mujoco / mujoco key not present, or LD_LIBRARY_PATH is not pointing to mujoco library'
+)
 def test_lstm_example():
     import tensorflow as tf
     from baselines.common import policies, models, cmd_util