Remove prelude imports

They cause conflicts with IntoIterator imports, and by removing the prelude
import instead of IntoIterator this enables continuing to work with 1.0.0-beta

phf/src/map.rs

@@ -1,6 +1,5 @@
 //! An immutable map constructed at compile time.
 use debug_builders::DebugMap;
-use std::prelude::v1::*;
 use std::borrow::Borrow;
 use std::ops::Index;
 use std::slice;

phf/src/ordered_map.rs

@@ -1,6 +1,5 @@
 //! An order-preserving immutable map constructed at compile time.
 use debug_builders::DebugMap;
-use std::prelude::v1::*;
 use std::borrow::Borrow;
 use std::iter::IntoIterator;
 use std::ops::Index;

phf/src/ordered_set.rs

@@ -1,6 +1,5 @@
 //! An order-preserving immutable set constructed at compile time.
 use debug_builders::DebugSet;
-use std::prelude::v1::*;
 use std::borrow::Borrow;
 use std::iter::IntoIterator;
 use std::fmt;

phf/src/set.rs

@@ -1,6 +1,5 @@
 //! An immutable set constructed at compile time.
 use debug_builders::DebugSet;
-use std::prelude::v1::*;
 use std::borrow::Borrow;
 use std::iter::IntoIterator;
 use std::fmt;