CMake integration, HTTP server support for keep-alive and compression

* Thanks to @delgor there's now CMake support for user projects.
  The needed find files are installed by default, thus a simple
    find_files(NuriaFramework)
  is enough to find everything related to the framework!
* Network: Support for keep-alive.
* Network: Support for outgoing filters, with implementations for
  Gzip and deflate transfer encoding (On-the-fly compression).