Merge remote-tracking branch 'jgallagher/master' into 2018

# Conflicts:
#	src/lib.rs
#	src/statement.rs

src/statement.rs

@@ -367,12 +367,7 @@ impl<'conn> Statement<'conn> {
         P::Item: ToSql,
     {
         let mut rows = self.query(params)?;
-        let exists = {
-            match rows.next() {
-                Some(_) => true,
-                None => false,
-            }
-        };
+        let exists = rows.next().is_some();
         Ok(exists)
     }