Nicer URLs for samples and sample files

[jeremysmithco]

I don't love the current URLs for samples and sample files:

/samples/4
/samples/4/files/11

I wonder if I should generate some longer hash ID instead of using the primary key, and maybe change the route names. Maybe something like this?

/s/oaf987dsf6d8f76dsf
/s/oaf987dsf6d8f76dsf/f/8dsf876sd9f8723

Maybe files shouldn't even be scoped through the sample.

/f/8dsf876sd9f8723