Automate creation of repl/fiddle

[kichik]

Right now you have to manually create a repl.it post for every snippet. We should create it on the fly or on build time using some API. This way there is no danger of the snippet being different than the runnable code.

There is also an option of using one of the embedding routes, but that means that if the snippet is purged or the embedded website goes down, our website becomes useless. Ideally I'd like to keep the snippet source in this repo.