Get rid of _param:influxdb_database

The StackLight database in InfluxDB is set to 'lma' by default. If one
wants to override it, it should be done in the user model.
diff --git a/heka/remote_collector/single.yml b/heka/remote_collector/single.yml
index 916308f..c18484f 100644
--- a/heka/remote_collector/single.yml
+++ b/heka/remote_collector/single.yml
@@ -6,7 +6,7 @@
     remote_collector:
       influxdb_host: ${_param:heka_influxdb_host}
       influxdb_port: ${_param:influxdb_port}
-      influxdb_database: ${_param:influxdb_database}
+      influxdb_database: lma
       influxdb_username: lma
       influxdb_password: ${_param:influxdb_stacklight_password}
       aggregator_host: ${_param:heka_aggregator_host}