added new RFAM benchmark data
Essentially, the fasta files contain the original RFAM sequences with added
random, dinucleotide shuffled buffer sequences on either end.
Normalised the sequence length to 250 nt. The difference is buffer.

Ex:
>ORIGINAL
CCCCCCCCCCGGGGGGGGGGG
.....(((.....))).....

>BUFFERED
AAAAACCCCCCCCCCGGGGGGGGGGAAAA
-----.....(((.....)))....----