Clippy cannot copy + signs

[lpgauth]

It seems that Clippy is unable to copy + signs.

To reproduce, using the rails helper, use the code bellow:
<%=h clippy("+++").html_safe %>

[lpgauth]

<%=h clippy(CGI.escape("+++")) %> works.

[ericabouaf]

Same thing for '&'
Maybe put in the README that if it is used for a URL, you need to encode it

[annie-l]

You can also replace the + in JS to encode it:

myString.replace("+", "%2B");