* Introduce `ReservableCurrency`
* Update Docs for `ReservableCurrency`
* Update Tests
* Bump spec and rebuild wasm
* Extra: Add a note to `slash()`
Discussion in Riot clarified the behavior of `slash()` and `can_slash()`. Trying to sneak clarifying comments about it into this PR
* Update lib.rs
* Don't drop the periods!
CC @shawntabrizi