Temporary solution to file polling problem

I've fixed the solution to the problem where files would be picked up and passed to processing layers while they were still copying to the filesystem (or still being created etc).

The Directory poller now checks to make sure at least 5 seconds have passed since the file was last modified. This should work for most cases (except for file copies over high latency networks and similar situations where a file might not be modified for more than 5 seconds even tho it is still in use).

I don't like this solution, as it makes data processing take 5 seconds longer than it needs to, plus for the reason mentioned above it's not a general solution, but it's the best I can do for now.

Another solution would to make the data copy to the polling directory with an special extention that the poller recognises and ignores, and have the extention removed when the data has finished being copied. The problem with this is it has to be implemented on the source's end, which may be able to be modified to conform to this protocol.