Specify wapm version as well

[ayys]

This script installs both wapm and wasmer. Right now, I can specify which wasmer version I want to install by

curl https://get.wasmer.io -sSfL | bash -s "<version>"

There should be something similar for wapm as well. Maybe something like this,

curl https://get.wasmer.io -sSfL | bash -s "<wasmer-version> <wapm-version>"