Allow Synapse log levels to be configured (#23)

roles/matrix-server/templates/synapse/synapse.log.config.j2

@@ -25,12 +25,12 @@ handlers:
 
 loggers:
     synapse:
-        level: INFO
+        level: {{ matrix_synapse_log_level }}
 
     synapse.storage.SQL:
         # beware: increasing this to DEBUG will make synapse log sensitive
         # information such as access tokens.
-        level: INFO
+        level: {{ matrix_synapse_storage_sql_log_level }}
 
 {% for logger in matrix_synapse_additional_loggers %}
     {{ logger.name }}:
@@ -38,5 +38,5 @@ loggers:
 {% endfor %}
 
 root:
-    level: INFO
+    level: {{ matrix_synapse_root_log_level }}
     handlers: [file, console]