Update to the 2018 edition

Only 2 years later :eyeroll:

src/helpers/cli.rs

@@ -1,9 +1,9 @@
 use std::io::{self, BufRead, Write};
 
-use errors::Result;
-use http_send::HttpSend;
-use registration::Registered;
-use Mastodon;
+use crate::errors::Result;
+use crate::http_send::HttpSend;
+use crate::registration::Registered;
+use crate::Mastodon;
 
 /// Finishes the authentication process for the given `Registered` object,
 /// using the command-line

src/helpers/env.rs

@@ -1,7 +1,7 @@
 use envy;
 
-use data::Data;
-use Result;
+use crate::data::Data;
+use crate::Result;
 
 /// Attempts to deserialize a Data struct from the environment
 pub fn from_env() -> Result<Data> {

src/helpers/json.rs

@@ -6,8 +6,8 @@ use std::{
 
 use serde_json;
 
-use data::Data;
-use Result;
+use crate::data::Data;
+use crate::Result;
 
 /// Attempts to deserialize a Data struct from a string
 pub fn from_str(s: &str) -> Result<Data> {

src/helpers/toml.rs

@@ -4,10 +4,10 @@ use std::{
     path::Path,
 };
 
-use tomlcrate;
+use crate::tomlcrate;
 
-use data::Data;
-use Result;
+use crate::data::Data;
+use crate::Result;
 
 /// Attempts to deserialize a Data struct from a string
 pub fn from_str(s: &str) -> Result<Data> {