Add tributary logic to maestro

1) extended tributary logic by avoiding copying duplicate files
2) refactored tributary logic so it is an Hdfs action
3) fixed tributary logic so that archive directory structure mimics HDFS source structure
4) changed tributary tests so they each run in an isolated directory
5) date parsing does not allow overflowed days and months
6) many other misc changes to tributary logic

Sorry about the size of the pull request :(
Good question: why _do_ they need to specify a time stamp format? Why don't we have a set of distinguishable time stamp formats which all our data providers agree to use, and then we can just check which one they are supplying us with? My guess is that getting all our data providers in line with this was considered impractical, but I don't really know.