Rename replace() to replaceWith() since Java 1.8 introduces Map.replace()

Java 1.8 brings Map[K, V].replace(), declared as  V replace(K key, V value).

This collides with replace declared on FluentCaseInsensitiveStringsMap and FluentStringsMap, which return the self type.

I therefore renamed the functions to replaceWith().

Alternative would be to change signature to return V and override Map's replace(), which however should not work on Java 6 and 7, I guess.