Return summary sending in datadog collector

[mstoykov]

In the #915 we are adding datadog collector to which @ivoreis added the ability to send summary data to datadog.
This has some problems - need to be configurable and the data has bash color sequences so I removed it in cb3a384 , but we would like it to have it in the future. It should also probably be done in a more centralized way :)

[olegbespalov]

We no longer have a datadog output, and the statsd also is moving to an extension, so we closing this issue as not planned.