Refactor - pysankey beta is now a third party lib

Use the beta version that we can update. And remove
dependency handled by pysankey

.isort.cfg

@@ -1,6 +1,6 @@
 [settings]
 multi_line_output=3
 line_length=88
-known_third_party =django,matplotlib,mock,numpy,pandas,pytz,seaborn,setuptools,yaml
+known_third_party =django,mock,pandas,pysankey,pytz,setuptools,yaml
 project = survey
 include_trailing_comma=True

requirements.txt

@@ -5,7 +5,4 @@ django-registration==2.2 # account logic, views and workflows
 pytz==2017.2
 ordereddict==1.1
 PyYAML==3.12
-pysankey==0.0.1
-matplotlib==2.1.0rc1
-seaborn==0.8.1
-numpy==1.13.3
+pySankeyBeta==1.0.1

survey/exporter/tex/question2tex_sankey.py

@@ -4,9 +4,9 @@
 
 from django.utils.translation import ugettext_lazy as _
 from pandas.core.frame import DataFrame
+from pysankey import sankey
 
 from survey.exporter.tex.question2tex import Question2Tex
-from pySankey.sankey import sankey
 from survey.models.question import Question
 
 LOGGER = logging.getLogger(__name__)
@@ -78,7 +78,7 @@ def tex(self, other_question):
             df[other_question.text],
             aspect=20,
             fontsize=10,
-            figure_name=name,
+            figureName=name,
         )
         return Question2TexSankey.TEX_SKELETON % (
             name[4:],