Annual Holiday with no offset or observance
 if observance is None and offset is None, Holiday breaks when Timestamp is added to None.  This was a bug in the 0.14.1 before a recent PR.  I will issue a pr for this shortly.  

Example:

```
    july_3rd = Holiday('July 4th Eve', month=7,  day=3)
```

July 3rd is a nyse exchange early close that is observed only  on July 3rd.
