Fix wrong jump if no count is specified
Fix wrong jump if no count is specified

If jump next hunk with no count, it move last hunk of below hunks.

v:count step is 0, 2, 3, 4..., so if no count is specified, next hunk is
-1(this is last hunk of below hunks).  Because of above reason, I change
to use v:count1 instead of v:count.  v:count1 step is 1, 2, 3, 4... .

Closes #40.

mhinz/vim-signify,jamessan/vim-signify