Migrate to Gatsby

[kbariotis]

Jekyll served us well but unfortunately, we've hit a point where development is not fun anymore and the tools right now seriously slow development. Moreover, Jekyll doesn't support modern mechanisms like code splitting and PWA features.

Gatsby is a modern static site generator based on React and Webpack while it implements a GraphQL server to feed data. It provides most of the functionalities we are looking for out of the box.

In order for us to do the migration though, there are is a thing we need to take care first and that is to remove the Bootstrap dependency which depends on a global layout stylesheet and on jQuery. Things we need to tackle are:

• [ ] Implement a Grid alternative, probably react-flexbox-grid
• [ ] Implement a responsive navigation top menu
• [ ] Implement an alternative to Bootstrap's tabs module
• [ ] Pass our data to Gatsby's GraphQL system in order to be used by the components

Other stuff might come out along the way and they will be stated here.

That would also be a great opportunity to get to know more Gatsby as it's a great and battle-tested tool.

@varemenos has already started working on the basis for the new project here

/cc @modkaffes @joskar @alexspyr Thoughts?