Add a "test_env" config value when running tests

The skill can check for this in their code

if 'test_env' in self.config_core:
    test_this()

allowing some basic workarounds in the skill init stage.

test/integrationtests/skills/skill_tester.py

@@ -43,11 +43,15 @@ from mycroft.messagebus.message import Message
 from mycroft.skills.core import create_skill_descriptor, load_skill, \
     MycroftSkill, FallbackSkill
 from mycroft.skills.settings import SkillSettings
+from mycroft.configuration import Configuration
 
 MainModule = '__init__'
 
 DEFAULT_EVALUAITON_TIMEOUT = 30
 
+# Set a configuration value to allow skills to check if they're in a test
+Configuration.get()['test_env'] = True
+
 
 # Easy way to show colors on terminals
 class clr: