Revert "Update reqs"

This reverts commit 55d2e24.

Author: shyuep

requirements.txt

@@ -1,15 +1,15 @@
 numpy==1.16.2
-scipy==1.2.1
-FireWorks==1.8.9
+scipy==1.2.0
+FireWorks==1.8.7
 pymatgen_diffusion==2019.2.28
-monty==2.0.3
+monty==2.0.2
 paramiko==2.4.2
 tqdm==4.31.1
 six==1.12.0
 pybtex==0.22.2
-ruamel.yaml==0.15.91
-pandas==0.24.1
-pymatgen==2019.3.27
+ruamel.yaml==0.15.89
+pandas==0.23.4
+pymatgen==2019.03.27
 custodian==2019.2.10
 networkx==2.2
-pydash==4.7.3
+pydash==4.7.3