Very much work in progress: fetch more complicated metrics with several dimensions
Improved the way configuration works

* In config.json metrics is now an object, not an array
* The key of this object is a unique identifier for the metric
* The DOM only holds this unique identifier
* The /data endpoint now only needs this unique parameter to fetch data
* You can specify any parameters that CloudWatch accepts in
  each metric's cloudwatch_params
* This enables the display of multi-dimensional metrics
Added back proxy check
Merge pull request #1 from samstarling/complex-metrics

Complex metrics