Fix POD for APIs of Teng::Schema::Table

Fix POD in `Teng::Schema::Table`, to fit to implementation (changed on badd7dd7a6b06c47c7393d0b542bab6a4df9b6e8):

* `#get_inflator()` and `#get_deflator()` are absent.
* `#set_inflator()` (and that for deflator) are not implemented.  Instead, `#add_inflator()` and `#add_deflator()` are defined.