Baremetrics date range picker vulnerable to Cross-site Scripting

The Baremetrics date range picker is a solution for selecting both date ranges and single dates from a single calender view. Versions 1.0.14 and prior are prone to cross-site scripting (XSS) when handling untrusted `placeholder` entries. An attacker who is able to influence the field `placeholder` when creating a `Calendar` instance is able to supply arbitrary `html` or `javascript` that will be rendered in the context of a user leading to XSS. There are no known patches for this issue.