Buffered appender to bulk endpoint

Here's a first version of a buffered loggly appender.
I didn't rip the whole thing apart so there are actually some pieces of the original implementation left.
The buffered appender buffers and also has a timer that flushes the buffer after a while if log frequency is too low.

I had a TinyIoCContainer in there but it felt like overkill, what do you think?

@joem-iq @stefanmoser 
This should be done by the client submitting the data, not the appender. Otherwise, we'll run into cases where people expect numeric values to be numbers and want to use mathematical comparisons.

Also, I don't think we should hack our appender because Loggly hasn't added a feature yet.