More features (#9)

* 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
* added type collectorContext to reduce the count of parameters for better readability
* added DHCP and DHCPv6 metrics
* filter for active dhcp leases only
* added pool metrics
* enable/disable feature in config file
* refactoring

* clean up

* comment fix

README.md

@@ -42,7 +42,7 @@ created for the exporter to use to access the API.
 where `config-file` is the path to a config file in YAML format.
 
 ###### example config
-```
+```yaml
 devices:
   - name: my_router
     address: 10.10.0.1
@@ -52,6 +52,13 @@ devices:
     address: 10.10.0.2
     user: prometheus2
     password: password_to_second_router
+
+features:
+  bgp: true
+  dhcp: true
+  dhcpv6: true
+  routes: true
+  pools: true
 ```
 
 ###### example output