Temporary BSD sed compat fixes

Temporary BSD sed compat fixes

BSD sed "-i" option requires an argument.  This temporary fix defines
SEDI as "sed -i ''" for BSD.

TODO: make this generally compatible with Linux by detecting the OS or
using sed (or similar) in a different manner.

Note:

sed -i '' works in BSD but not Linux.
sed -i''  works in Linux but not BSD.

Signed-off-by: Bill Erickson <berick@esilibrary.com>