Ensure touching files works outside of the top-level directory
Ensure touching files works outside of the top-level directory

Related to #9, this fixes up some other uses where the paths used by
certain commands are not relative to the current directory. This would
cause strange bugs when running certain transcrypt commands from
somewhere besides the top-level directory.

elasticdog/transcrypt,TechEnterprises/transcrypt,spector-in-london/transcrypt