Simple Flash Pseudo-streaming

Optional support for Flash pseudo-streaming. By default pseudo-streaming is not enabled, but can be enabled by setting a new option: enablePseudoStreaming=true. When enabled, a seek within the buffer range will continue to use the existing stream's buffer, but a seek outside the buffer will include a query parameter to pull down a new byte range. By default the query parameter is set to 'start', but can be changed for other CDN/streaming servers by setting the pseudoStreamingStartQueryParam option. For now only mp4 support is included but flv support wouldn't be too hard to add.