Fix issue https://github.com/emoncms/emoncms/issues/129

Hours, minutes, seconds now have "0" prepended if they're < 10, so you get 01:01:01 rather then 1:1:1 for 1 am, 1 minute, 1 second.
Tooltips now behave the same on both the multigraph and the rawdata plots.
I also added the fadein behaviour from the multigraph tooltips to the rawdata plot as well, since it's cool and looks nice.