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 
Why not make the post synchronous then?  It's already executing on another thread because of the `Timer`, so what benefit are you getting by making the post async?  It wouldn't block events from being logged.