Add java docs (or equivalent) for SDK

We're going to use github pages to host our code and class reference.

What we need:
- Create a branch named `gh-pages` from the initial empty commit of the repo
- Add README.md , .gitignore
- Add branch master as a submodule: `git submodule add `
- Add scripts to build the docs and publish(commit/push) them

For reference see the repo https://github.com/Criptext/Monkey-SDK-iOS