Removed HtmlCompressor

Turns out HtmlCompressor was our performance bottleneck.

It is basically a lot of regexes operating on really large string.

Attached is a graph showing article latency dropping in half after removing it and here is a jstack snippet showing threads stuck there...

This pull request also includes a switch to the Apache Async library. I like a library that you can actually get stats out of.

```
"play-akka.actor.default-dispatcher-28" prio=10 tid=0x00007f156c040000 nid=0x9ad runnable [0x00007f15991ef000]
   java.lang.Thread.State: RUNNABLE
	at com.yahoo.platform.yui.compressor.CssCompressor.<init>(CssCompressor.java:28)
	at com.googlecode.htmlcompressor.compressor.YuiCssCompressor.compress(YuiCssCompressor.java:44)
	at com.googlecode.htmlcompressor.compressor.HtmlCompressor.compressCssStyles(HtmlCompressor.java:860)
	at com.googlecode.htmlcompressor.compressor.HtmlCompressor.processStyleBlocks(HtmlCompressor.java:792)
	at com.googlecode.htmlcompressor.compressor.HtmlCompressor.processPreservedBlocks(HtmlCompressor.java:658)
	at com.googlecode.htmlcompressor.compressor.HtmlCompressor.c
```

![latency](https://f.cloud.github.com/assets/76709/496624/4edbd6dc-bbe6-11e2-8bed-0cd5d1113f18.png)