Make LevelDB sample keys fixed-length to ensure correct sort-order.
Merge pull request #132 from prometheus/julius-leveldb-sorting

Make LevelDB sample keys fixed-length to ensure correct sort-order.
Also allow lower-cased aggregation ops.
Merge pull request #124 from prometheus/julius-lowercase-ops

Also allow lower-cased aggregation ops.
Render graph labels vertically

This helps to make the timeseries with many labels fit on the screen.
Hovering over legend items highlights series in graph
Render legend in a similar style to labels
Flip hover detail to prevent going off the screen