Java: nucleotide-count: sync sample solution and test class names

[FridaTveit]

As far as I'm aware it's best practice to name a test class after the class it's testing. So if you're testing SomeClass you would name the test class SomeClassTest. We usually do this but in nucleotide-count we have NucleotideTest which test the class DNA. I suggest we:

1. Rename NucleotideTest to DNATest (or possibly Dna and DnaTest to make it more readable?)
2. Add this preference to the POLICIES doc

Do you agree with this @exercism/java?

[Smarticles101]

What if we renamed the DNA class to Nucleotide or NucleotideCount? Normally, the solution class is named after the exercise. Other than that, I think adding what you said to the POLICIES doc is a great idea.

[stkent]

+1 NucleotideCount, or even NucleotideCounter.
+1 a new entry under the 'best practices' section of the policies.