precompile assets for production

[bioform]

In production I serve my assets via nginx, so all assets should be precompiled.
They can be precompiled during server startup (see #10 ) or
"assets-compiler" should add new command to compound like:

compound assets precompile
# or short form
compound a precompile

[bioform]

this is critical issue since it is impossible to use compound in production without it.
web server should be able to serve static assets instead of nodejs