Add support for target wasm32-unknown-unknown

[peerhenry]

As a developer I would like to have the option of choosing the wasm32-unknown-unknown target.
rust-lang/rust#45905

[germania]

I have a working version of this as of last night, the boilerplate is actually way cleaner... Have to clean things up but I'm hoping to submit a PR this weekend

[germania]

Added in #10

[ianjsikes]

@peerhenry wasm32-unknown-unknown support is merged in. Great work @germania .