VOL-2496 Add "event listen" command to voltctl

Change-Id: I8f1fb34b55f56c8125142ac289e2f19fc170d804
diff --git a/go.sum b/go.sum
index 4105b2c..35413d4 100644
--- a/go.sum
+++ b/go.sum
@@ -2,14 +2,28 @@
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@@ -23,6 +37,8 @@
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@@ -36,11 +52,15 @@
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@@ -50,6 +70,13 @@
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@@ -58,17 +85,25 @@
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@@ -93,6 +128,7 @@
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@@ -124,6 +160,16 @@
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