[del] remove rest API

Tiscaf was originally designed to be a minimalistic http server. Over
time it gained some new features, such as more HTTP verbs supported and
SSL support. These features make sense for a raw minimalistic HTTP
server (one could object that they don't, but they are not completely
irrelevant in this context).
However, Rest API support is definitively out of scope, and should no
longer live directly in the tiscaf project. Its place would better be in
a specific `tiscaf-rest` module
[imp] modular infrastructure

Prepare the directory structure for modules that may and will appear
soon (the first will be Rest API support).
[new] add Rest API support