Wee need to upload some results to Rosalind to check how it works. We cannot 
currently upload the solution for "Finding All Similar Motifs" problem because
wee need to solve some earlier problems.

Thus, our job now is to:

* write a class to solve this problem https://rosalind.info/problems/dna/
* use already existing class (e.g. Sequence) which reads FASTA file
* upload the results in Rosalind to check whether it works. On the bottom
  of the https://rosalind.info/problems/dna/ page there is a button 
  "Download dataset"