Build packages with customized plugins, configurations and package name

Change many build scripts to build customized plugins, configurations and package names.
And separate `td` command and `td-agent-ui` from `td-agent-files` to build packages without them. In some environment, `td` command is not safe to use, and `td-agent-ui` make binary package too fat.

`files` directory is removed. Files in `files/etc` are moved to `templates`, and other files are not used.

I tested this patch for rpm package, but not tested about deb/dmg/pkg yet. I have no environment for that.
Could you test them? @repeatedly