message: Add impl ToSql for Cow<str> (see
diff: use fallible_iterator::FallibleIterator;
  use postgres_protocol;
  use postgres_protocol::types::{self, ArrayDimension};
  +use std::borrow::Cow;
  use std::collections::HashMap;
  use std::error::Error;
  use std::fmt;
  @@ -635,6 +636,18 @@ impl<'a> ToSql for &'a str {
  to_sql_checked!();
  }
  +impl<'a> ToSql for Cow<'a, str> {
  + fn to_sql(&self, ty: &Type, w: &mut Vec<u8>) -> Result<IsNull, Box<Error + Sync + Send>> {
  + <&str as ToSql>::to_sql(&&self.as_ref(), ty, w)
  + }
  +
  + fn accepts(ty: &Type) -> bool {
  + <&str as ToSql>::accepts(ty)
  + }
  +
  + to_sql_checked!();
  +}
  +
  impl ToSql for String {
  fn to_sql(&self, ty: &Type, w: &mut Vec<u8>) -> Result<IsNull, Box<Error + Sync + Send>> {
  <&str as ToSql>::to_sql(&&**self, ty, w)
  