Sink specific configuration maps (#25)

* Use sink-specific configurations to have more flexibility. Adjust sample sink configuration files

* Add documentation

* Add links to individual sink readmes

* Fix link in README

* HTTPS for HttpSink

* If no CPU die id available, use the socket id instead

sinks/gangliaSink.md

@@ -0,0 +1,21 @@
+## `ganglia` sink
+
+The `ganglia` sink uses the `gmetric` tool of the [Ganglia Monitoring System](http://ganglia.info/) to submit the metrics
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "ganglia",
+    "meta_as_tags" : true,
+    "gmetric_path" : "/path/to/gmetric",
+    "add_ganglia_group" : true
+  }
+}
+```
+
+- `type`: makes the sink an `ganglia` sink
+- `meta_as_tags`: print all meta information as tags in the output (optional)
+- `gmetric_path`: Path to `gmetric` executable (optional). If not given, the sink searches in `$PATH` for `gmetric`.
+- `add_ganglia_group`: Add `--group=X` based on meta information to the `gmetric` call. Some old versions of `gmetric` do not support the `--group` option.