BioSequences v0.8.0

Feature additions

• Position weight matrix search (#16).
• Generalised composition method (#22).
• typemin and typemax methods have been added for Kmer types (#20).

Patches and fixes

• Dictionaries now used to store counts in Composition types (#21).
• MinHash function is now generalised to Reader types (#19).
• Doctests have been updated to julia v0.6 (#18).