api/auth: add package-level ErrInvalidUsername and ErrInvalidPassword
api/auth/auth_test: add a full authentication cycle test
Makefile: remove cross-compile directives, because we use cgo
config/cliConfig: initial commit, and use CLI config instead of JSON
config: move JSON configurations to jsonFileConfig
.travis.yml: fix test mock media path
README: show CLI configuration, remove all JSON configuration
data/db_sqlite: always create database if it doesn't exist
Merge branch 'master' into dev_subsonic_api