Remove the last remnants of `emysql:modules()`.
Remove a TODO.

In Erlang `<<1>>` codes a bit as the 8-bit value 0x1. If we wrote `<<"1">>`, we will get
the ascii character for 1, which is 49 or 0x31. It is probably more correct to return the
0x1 value.
The conversion tests can safely run in parallel.