config: Introduce config initialization.

When application starts, check conf/application.conf and if the file
does not exist, copy from conf/application.conf.default.

Remove conf/application.conf and conf/application.user.conf because they
are no more needed.

minor: Fix whitespace errors in application.conf.default.
Merge pull request #355 from npcode/feature/application.conf.default

config: Introduce config initialization.