Porting FASTQ IO

This a step towards porting FASTQ over to skbio.io as addressed in #681

I have a sniffer and reader written up and added some additional formatting checks.
Also, I would like to add an additional doctest to test to for phred-offset=64, 
but I'm not sure how to do it.  
Since you know the `phred_offset` at this point, it is worth returning in the dictionary.