Rearrange source tree.

 * Move Go package into `pkg' folder.
 * Move binaries to the top `cmd' folder.
 * Move server static files into `cmd/facette'.
 * Rewrite Makefile.
 * Rewrite third-party handling.
 * Add third-party packages into the repository.
Rearrange packages.

 * Split `common' package into `config' and `types' ones.
 * Move struct and types to `types' package.
 * Update `Makefile' and tests configuration files.
Clean up code from superfluous var definitions.
Add missing `build-bin' targets in `Makefile'.