Move resistor color to later in the track and bump the difficulty

[ryanplusplus]

Addresses #840

[fapdash]

Looks fine for me regarding #840 but it might make sense to improve the ordering overall, maybe in an extra PR. There is currently a thread in the forum about practice exercise ordering: #840 I know that reordering all the exercises can be a lot of work but as a small improvement, for me two-fer and leap are two obvious candidates to put very early since you can solve both of them with a single line statement.

Edit: looking at the two-fer solution in C I guess it's not so obvious with the buffer and all, I think I know too little about C to make useful suggestions, sorry.