I stumbled on this last night, Salesforce is behind this;
https://www.heroku.com/
Probably, they will boot you out for adult but they offer free accounts there and you could see what they are up to -- it looks very slick.
https://www.heroku.com/policy/aup
Heroku contributors also use github extensively so you can get a lot of the source code to use.
HTML5 is the way to go BTW unless your customer will download an app from a shady source -- remember dialers :OP