Remove default values.

app/main/forms.py

@@ -21,7 +21,7 @@ class AddCorpusFileForm(FlaskForm):
 class CreateCorpusForm(FlaskForm):
     description = StringField('Description',
                               validators=[DataRequired(), Length(1, 64)])
-    submit = SubmitField('Create corpus')
+    submit = SubmitField()
     title = StringField('Title', validators=[DataRequired(), Length(1, 32)])