Runner loads app from app dir instead by app id

Refactoring of WebAppRegistry and WebApp classes needed.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Fix usage of app_name, app_id, app_uid, ...

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Rename main.vala of binaries to better names

nuvolaplayer/main.vala -> master/master.vala
apprunner/main.vala -> apprunner/apprunner.vala

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>