News features and improvements (#8)

* added config file implementation, refactoring

* add gitignore

* improved test

* preperations for more metrics

* added resource metrics

* added first bgp metrics

* added asn as label for bgp metrics

* added prefix and message counts to bgp metrics

* simplified

* Update README.md

* added yaml dependency

* fixed go routine call

* added timeout

* clean up

* added TLS support

* set default api port for TLS

* added routes metric

* added missing log information

README.md

@@ -35,6 +35,25 @@ where `address` is the address of your router. `device` is the label name for th
 in the metrics output to prometheus. The `user` and `password` are the ones you
 created for the exporter to use to access the API.
 
+#### Config File
+
+`./mikrotik-exporter -config-file config.yml`
+
+where `config-file` is the path to a config file in YAML format.
+
+###### example config
+```
+devices:
+  - name: my_router
+    address: 10.10.0.1
+    user: prometheus
+    password: changeme
+  - name: my_second_router
+    address: 10.10.0.2
+    user: prometheus2
+    password: password_to_second_router
+```
+
 ###### example output
 
 ```
@@ -47,4 +66,4 @@ mikrotik_interface_tx_byte{address="10.10.0.1",interface="ether7",name="my_route
 mikrotik_interface_tx_byte{address="10.10.0.1",interface="ether8",name="my_router"} 1.86405031e+08
 ```
 
- 
+