Strip unused paths from the settings

[andyneff]

When terra starts a runner, not all paths in the settings will be translates for a particular service because they are not always used. There is room for a process to strip unused paths.

Pros:

• Less confusion for users who see a mixture of translated and untranslated paths
• By removing the ability to use a path that is not translated, it prevents them from using it incorrectly when the paths should not be used in that service (without adding it to the service definition)

Cons:

• When a file is written in the service runner, if it contains absolute paths, it would need patching. If someone was using an untranslated setting to accomplish this, it would break. But they really shouldn't be doing it this way.