Bug Fix for Issue #513 Fractional seconds lost in HDFStore for datetime indexes
PyTables Time64Col is in fact a float64 alias so adding fractional seconds and using the correct dtype fixes this issue
#513

Looks pretty good to me. Will let Wes look before I merge it in...
 indeed this looks fine. thanks a lot!
 hi @lespaul, because you made a pull request from your master branch, you will want to `git fetch upstream` and then `git reset --hard upstream/master`
