Ensure type config values are strings before applying

[VoxSecundus]

Currently, the profile apply process maps the type question config values to strings and tries to interpolate them into the command spawned out. If a config value isn't a string, and cannot be implicitly converted to a string, an error is raised. We should either (1): only accept string values for config keys, or (2): try and convert all values to strings before submitting, raising a more user-friendly error if any of them cannot be converted.

[VoxSecundus]

Resolved in #56 .