FIX: Several minor fixes

This addresses an issue where epochs that were saved could not be loaded. Related to a previous PR where `evoked.first` and `evoked.last` were updated to be set in this same manner, for the same reason.

Also includes some minor fixes to KIT support. @t3on, a few minor suggestions for future commits:

1. In testing, we don't do relative imports, but instead use absolute ones. I'm not 100% sure why, but it's our convention (maybe @agramfort has a reason).

2. By convention, tests are also stored in a directory named `tests`, not `test`. Nitpicky I know, but these things can come back to haunt us later if we're not careful.

2. Try to pay attention to warnings in testing. We try to eliminate warnings we get, and some can be informative. Note that one I've fixed here is that you had been doing a `/=` from an integer (created by `np.arange`) to float, which would cause an error in a future version of numpy. I've changed it to be float from the beginning so there would be no such warning. There was also a warning about the use of `pick_types` in the kit code that I have fixed as well. It's better if users don't encounter warnings in regular use unless they are doing something potentially dangerous.