Add CI using GitHub Action

Add CI using GitHub Action

Same setup than Travis except for removing
`rm -f target/debug/lightning-*` as I do not believe
such file would exist on a fresh run.

I have not setup caching at this stage. The library is
small so I don't think it'd be that necessary/helpful.

I'd recommend to let both CI run for a bit to compare
performance and stability. The CI setup is straightforward
so I do not foresee any issue with GitHub actions.

Once happy, Travis file can be removed and branch
protection checks can be updated to block on the GitHub
actions.

You can also check the [Coverage report](https://codecov.io/gh/D4nte/rust-lightning/tree/752a58bc0441a49a0513f2cad979ad9e2621312a/lightning/src/chain) to ensure it is as expected.