pin python versions using requirements.txt.

Makefile

@@ -128,7 +128,7 @@ pyenv:
 	python3 -m venv pyenv
 	. pyenv/bin/activate && \
 		pip install -U pip && \
-		pip install autopep8 azdev azure-mgmt-loganalytics==0.2.0 colorama ruamel.yaml wheel && \
+		pip install -r requirements.txt && \
 		azdev setup -r . && \
 		sed -i -e "s|^dev_sources = $(PWD)$$|dev_sources = $(PWD)/python|" ~/.azure/config
 

requirements.txt

@@ -0,0 +1,5 @@
+autopep8==1.6.0
+azdev==0.1.37
+azure-mgmt-loganalytics==0.2.0
+colorama==0.4.5
+ruamel.yaml==0.17.21