Remove special utf8 handling

This basically reverts two commits:

 - d252369
 - f0d4aaa

Unfortunatlye I did a poor job documenting the reason for these commits.
But they both seem to have "broken" things, and now I'm unsure exactly
what they *fixed*.

bin/dots

@@ -75,7 +75,6 @@ from __future__ import print_function
 
 import sys
 import os
-import io
 import shutil
 import subprocess
 import glob
@@ -220,7 +219,7 @@ class Configuration(object):
         exist in the source tree (meaning it's considered an 'invalid group'"""
         if not os.path.exists(self.group_file): return
 
-        with io.open(self.group_file, 'r') as f:
+        with open(self.group_file, 'r') as f:
             self.groups = f.read().splitlines()
 
         if not self.groups:
@@ -235,7 +234,7 @@ class Configuration(object):
         if not os.path.exists(directory):
             os.makedirs(directory)
 
-        with io.open(self.group_file, 'w+') as f:
+        with open(self.group_file, 'w+') as f:
             f.write('\n'.join(self.groups))
 
     def files(self, path_filters=None):
@@ -376,7 +375,7 @@ class ConfigFile(object):
         append_points = set()
 
         for path in self.real_paths():
-            with io.open(path, 'r') as file:
+            with open(path, 'r') as file:
                 for line in file:
                     line = line.strip()
                     if line.startswith(AP_IDENTIFIER):
@@ -422,7 +421,7 @@ class ConfigFile(object):
         # Read all file paths into arrays
         # This may be memory inefficient and may have to be changed later
         for path in self.real_paths():
-            with io.open(path, 'r') as file:
+            with open(path, 'r') as file:
                 contents = file.readlines()
 
                 # Replace front and back empty lines with None
@@ -519,18 +518,18 @@ class ConfigFile(object):
 
         # Test that the file hasn't changed
         if os.path.exists(path):
-            compiled = ''.join(self.compiled).encode('utf-8')
+            compiled = ''.join(self.compiled)
             compiled = hashlib.md5(compiled).digest()
 
-            with io.open(path, 'r', encoding='utf-8') as installed_file:
-                installed = installed_file.read().encode('utf-8')
+            with open(path, 'r') as installed_file:
+                installed = installed_file.read()
                 installed = hashlib.md5(installed).digest()
 
             if installed == compiled and os.stat(path).st_mode == self.mode():
                 return
 
         # Write the file
-        with io.open(path, 'w') as file:
+        with open(path, 'w') as file:
             file.writelines(self.compiled)
 
         # Set the file's mode