add some version specifiers in requirements (#281)

opt-requirements.txt

@@ -2,6 +2,6 @@ pillow
 scipy
 h5py
 tornado; python_version < '3.0'
-lmdb
+lmdb>=0.92
 matplotlib
 scikit-learn

requirements.txt

 numpy
 six
-termcolor
-tabulate
+termcolor>=1.1
+tabulate>=0.7.7
 tqdm>4.11.1
-msgpack-python
-msgpack-numpy
+msgpack-python>0.4.0
+msgpack-numpy>=0.3.8
 pyzmq>=16
 subprocess32; python_version < '3.0'
 functools32; python_version < '3.0'