Migrate remaining modules to use get_bin_path in module_common.py

* Migraed easy_install, pip, service, setup, and user.
* Updated fail_json message in apt_repository
* Fixed easy_install to not hardcode location of virtualenv in
  /usr/local/bin/.
* Made handling of virtualenv more consistent between easy_install and
  pip.

library/service

@@ -39,10 +39,7 @@ def _find_binaries(m):
         location[binary] = None
 
     for binary in binaries:
-        for path in paths:
-            if os.path.exists(path + '/' + binary):
-                location[binary] = path + '/' + binary
-                break
+        location[binary] = m.get_bin_path(binary)
 
     if location.get('systemctl', None):
         CHKCONFIG = location['systemctl']