Replace all instances of unicode only handling to use force_text.

Replace all __unicode__ methods to __str__ and the
@python_2_unicode_compatible decorator.
Replace all instance of smart_str, smart_unicode, force_uncode
with force_text.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/common/widgets.py

@@ -2,7 +2,7 @@ from __future__ import unicode_literals
 
 from django import forms
 from django.forms.utils import flatatt
-from django.utils.encoding import force_unicode, force_text
+from django.utils.encoding import force_text
 from django.utils.html import conditional_escape, format_html
 from django.utils.safestring import mark_safe
 from django.utils.translation import ugettext_lazy as _
@@ -122,7 +122,7 @@ class TextAreaDiv(forms.widgets.Widget):
             value = ''
 
         flat_attrs = flatatt(self.build_attrs(attrs, name=name))
-        content = conditional_escape(force_unicode(value))
+        content = conditional_escape(force_text(value))
         result = '<pre%s>%s</pre>' % (flat_attrs, content)
         return mark_safe(result)