Make test names match assertions

First it looked like each test name was backwards. Giving the function "C" and transcribing to "G" was named `transcribes-guanine-to-cytosine` rather than `transcribes-cytosine-to-guanine`.

Second, the assertion for "T" -> "A" appeared to be in the right order but it mentioned the wrong nucleotide.
Merge pull request #26 from mitchlloyd/patch-1

Make test names match assertions