Use new flash API call to obtain erase value instead of relaying on hardcoded literals. Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
Added basic tests for the NVS file system. One of the tests covers power down during the flash write operation. Signed-off-by: Kamil Piszczek <Kamil.Piszczek@nordicsemi.no>