Add arrayVectorOps and randomNumbers to primers/Makefile

These two new primers didn't get added to the primers Makefile until now.
Update the name of primer random to randomNumbers in READMEs

The name of this primer changed to avoid a name conflict on case sensitive
filesystems.
Merge pull request #508 from daviditen/primersMakefileUpdate

Add arrayVectorOps and randomNumbers to primers/Makefile

We forgot to add these two to the primers/Makefile. Add them. Also, updated the name of random to randomNumbers in two READMEs.
[reviewed by lydia-duncan]