prepare change log for v0.7.2 release

ccoffrin · web-flow · commit 31e7627c4844 · 2018-06-01T13:50:41.000-04:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,9 @@ PowerModels.jl Change Log
 =================
 
 ### Staged
+- nothing
+
+### v0.7.2
 - Removed Memento depreciation warnings
 
 ### v0.7.1
