Imperial <-> Metric Conversion

[janine9vn]

Context

The Americans and non-Americans on the server have requested functionality for Lovelace to convert imperial units to metric.

Details

• This should result in a new Cog that is added.
• It should have it's own command to invoke it. (i.e. "!convert")
• It should work for the basics units (i.e. temperature, mass, force, length).
• It should work to convert imperial to metric and vice-versa.