fix locate broken since 63799b01985c - fix the keyword arguments for walk in commands.locate - implement 'hg locate -r <rev>' - add a test for 'hg locate'

adding foo
adding bomb
adding a.c
adding dir/a.o
adding dir/b.o
! a.c
! dir/a.o
! dir/b.o
? .hgignore
a.c: unsupported file type (type is fifo)
! a.c