Extended instructions

This changes ```Path.calcInstructions()``` to return a ```List<Instruction>``` instead of a ```InstructionList```.
One instance of ```Instruction``` represents one segment of a route / path and additionally contains the time in seconds to cross the segment and lat/lon coordinates of the beginning of the segment. 

In addition to that, I also changed the web app to show the times in the list of instructions and to open a popup in the map when hovering over an instruction. 

![graphhopper](https://f.cloud.github.com/assets/640185/1723897/1327e890-6264-11e3-8471-c599a65b81ce.png)

I would greatly appreciate it if this could be merged into the main project. 

This should fix issue #110