Issue-7: add updated tests for NYSE NYE update

nyse.yaml

@@ -4,6 +4,9 @@
 # Source: http://www.nyse.com/about/newsevents/1176373643795.html#earlyclose2008
 #
 # Updated 2008-11-19.
+#
+# Source: https://www.nyse.com/markets/hours-calendars
+# Updated 2017-03-14 By Vassilios Liatsos
 ---
 months:
   0:
@@ -15,6 +18,7 @@ months:
   - name: New Year's Day
     regions: [nyse]
     mday: 1
+    observed: to_monday_if_sunday(date)
   - name: Martin Luther King, Jr. Day
     week: 3
     regions: [nyse]
@@ -56,6 +60,12 @@ tests:
       regions: ["nyse"]
     expect:
       name: "New Year's Day"
+  - given:
+      date: ['2017-01-02', '2012-01-02', '2011-01-01', '2006-01-02']
+      regions: ["nyse"]
+      options: ["observed"]
+    expect:
+      name: "New Year's Day"
   - given:
       date: '2008-01-21'
       regions: ["nyse"]