Update README.md

Exclude the script directory from the release. The major reason is that the Flow tests doesn't work because Flow is not released. If anyone is interested, I could send them via email.
Merge pull request #3 from ydmao/patch-1

Update README.md
no more table_lookup in masstree-release
no more ckptrav_order_t in masstree-release
avoid double configuration of KVDB_ROW_TYPE_ID
kvproto nits