Add seaborn as a standard fslpython lib

fslpython_environment.yml

@@ -23,6 +23,7 @@ dependencies:
  - isodate=0.5.4
  - mkl-service=1.1.2
  - scikit-image=0.13.1
+ - seaborn=0.8.1
  - pip:
    - SPARQLWrapper==1.7.6
    - rdflib==4.2.1