pandas 0.13+ required
finally iawe metadata can be loaded. Needs a lot more work to get accurate..but this is a decent start
removed conversion of nanosecond timestamp to integer
Merge branch 'master' of https://github.com/nilmtk/nilmtk
No longer necessary to multiply UNIX epoch timestamps by 1E9, instead
can use `unit='s'`. This should be even safer against int overflows
on different platforms. #131
Tidy up comments in `_load_data()`