Fix the handling of modulemd files with unicode characters.

This commit introduces new to_text_type helper method and calls it
for return value of all mmd.dumps() calls. That way, we always
end up with proper unicode string represntation on both python
major versions.

This commit also adds unicode character to description of all
the yaml files we use in the tests so we can be sure MBS can
handle unicode characters properly.

This might be temporary fix, depending on the result of discussion
at https://github.com/fedora-modularity/libmodulemd/issues/184.

tests/test_scheduler/test_module_init.py

@@ -24,6 +24,7 @@ import yaml
 
 from mock import patch, PropertyMock
 from gi.repository import GLib
+from module_build_service.utils import to_text_type
 
 from tests import conf, clean_database
 from tests.test_views.test_views import FakeSCM
@@ -42,7 +43,7 @@ class TestModuleInit:
         testmodule_yml_path = os.path.join(
             self.staged_data_dir, 'testmodule_init.yaml')
         with open(testmodule_yml_path, 'r') as f:
-            yaml = f.read()
+            yaml = to_text_type(f.read())
         scmurl = 'git://pkgs.domain.local/modules/testmodule?#620ec77'
         clean_database()
         with make_session(conf) as session:
@@ -78,7 +79,7 @@ class TestModuleInit:
         filter_list.add("foo")
         filter_list.add("bar")
         mmd.set_rpm_filter(filter_list)
-        platform_build.modulemd = mmd.dumps()
+        platform_build.modulemd = to_text_type(mmd.dumps())
         db.session.commit()
 
         msg = module_build_service.messaging.MBSModule(
@@ -137,7 +138,7 @@ class TestModuleInit:
         includedmodules_yml_path = os.path.join(
             self.staged_data_dir, 'includedmodules.yaml')
         with open(includedmodules_yml_path, 'r') as f:
-            yaml = f.read()
+            yaml = to_text_type(f.read())
         scmurl = 'git://pkgs.domain.local/modules/includedmodule?#da95886'
         with make_session(conf) as session:
             ModuleBuild.create(