update dependencies to match component-init

* eliminate dependency on wasm-convert
* for the moment, using my branch of component-init. we should publish
  to crates.io once this is validated.
* update to wasm-tools versions matching component-init
* update wasmtime to latest, not required but just nice to do while
  we're here
* eliminate wasi-common dependency, which is unnecessary

Author: pchickey