add special color file for test

backend/color-test.json

+{
+  "primary": "#7d4e24",
+  "contents/html-document": "#3f52e3",
+  "contents/thread": "#ad4cf9",
+  "contents/file": "#ff9900"
+}

backend/tests_configs.ini

 user.auth_token.validity = 604800
 preview_cache_dir = /tmp/test/preview_cache
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json
+
 [app:command_test]
 use = egg:tracim_backend
 sqlalchemy.url = sqlite:///tracim_test.sqlite
 user.auth_token.validity = 604800
 preview_cache_dir = /tmp/test/preview_cache
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json
 
 [mail_test]
 sqlalchemy.url = sqlite:///:memory:
 email.notification.smtp.user = test_user
 email.notification.smtp.password = just_a_password
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json
 
 [mail_test_async]
 sqlalchemy.url = sqlite:///:memory:
 email.notification.smtp.user = test_user
 email.notification.smtp.password = just_a_password
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json
 
 [functional_test]
 sqlalchemy.url = sqlite:///tracim_test.sqlite
 preview.jpg.restricted_dims = True
 email.notification.activated = false
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json
 
 [functional_test_no_db]
 sqlalchemy.url = sqlite://
 preview.jpg.restricted_dims = True
 email.notification.activated = false
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json
 
 [functional_test_with_mail_test_sync]
 sqlalchemy.url = sqlite:///tracim_test.sqlite
 email.notification.smtp.user = test_user
 email.notification.smtp.password = just_a_password
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json
 
 [functional_test_with_mail_test_async]
 sqlalchemy.url = sqlite:///tracim_test.sqlite
 email.notification.smtp.user = test_user
 email.notification.smtp.password = just_a_password
 website.base_url = http://localhost:6543
+color.config_file_path = %(here)s/color-test.json