UNDERTOW-118 TCCL not set on HttpUpgradeHandler invocation
- improves performance of HttpString#appendTo(ByteBuffer)
  by using the bulk put method of ByteBuffer.
  Subclasses of ByteBuffer provide optimized implementations of
  the bulk put method which does not use a loop over the byte array.
Change websockets to add the filter on demand
UNDERTOW-112 Fix chunking performance issues by using writeFinal to write the chunk terminator
Fix NPE
Add option to ignore explicit flush for performance reasons
UNDERTOW-117 Implement cache expiration for files based on the Xnio watch service
UNDERTOW-119 Exception in ReadListener.onDataAvailable() may cause infinite loop