docs(docs/*): Docs refactored to enable static site generation.

The documentation is now a combination of Markdown and Jinja2 syntaxes. This
allows devs to have more fine-tuned control over how they are presented.

In this case, Jinja will render the docs into HTML -- injecting any variables
and rendering based on templating logic -- from Markdown which serves as the
primary markup syntax.

Breaking changes: Lots of broken links on SO.
fix(docs): restructure
docs: Continuing revamp of documentation structure
docs: Change links from `user/` to `integrating/`
docs: Fix links to blog and other doc sites

Final touches on the first round of documentation generation sans GitHub.
docs: Static doc generation

Using a tool called [docfu](https://github.com/feltnerm/docfu), the documentation
for FineUploader is now generated on a per-push basis and hosted on a new website:

    docs.fineuploader.com

This enables greater control and customization of the documentation to better
target end-users (especially compared to what GitHub had previously).