Simply embed tweets in Jekyll posts with liquid tags, which seems to work.
This uses a liquid tag called llazy_embedtweet, if you come up with a better one please tell me. I was tired when I named it.
Put the less_lazy_tweet_embed.rb file in the _plugins folder of the Jekyll site (basically in the same folder that _posts is in),
but make sure that plugins are enabled! (so no using this with GitHub pages...)
Then to embed a tweet, use the tags.
For example: {% llazy_embedtweet https://twitter.com/skyem123/status/685987008553050113 %}, will embed the tweet https://twitter.com/skyem123/status/685987008553050113 inside the post.
This is under the ISC (similar to the 2-clause BSD) licence, but is based off of code under the MIT licence, look in LICENCE.txt for details.