Fix pylint errors specific to python3

Author: rbeagrie

.pylintrc

@@ -65,7 +65,7 @@ confidence=
 # --enable=similarities". If you want to run only the classes checker, but have
 # no Warning level messages displayed, use"--disable=all --enable=classes
 # --disable=W"
-disable=import-star-module-level,old-octal-literal,oct-method,print-statement,unpacking-in-except,parameter-unpacking,backtick,old-raise-syntax,old-ne-operator,long-suffix,dict-view-method,dict-iter-method,metaclass-assignment,next-method-called,raising-string,indexing-exception,raw_input-builtin,long-builtin,file-builtin,execfile-builtin,coerce-builtin,cmp-builtin,buffer-builtin,basestring-builtin,apply-builtin,filter-builtin-not-iterating,using-cmp-argument,useless-suppression,range-builtin-not-iterating,suppressed-message,no-absolute-import,old-division,cmp-method,reload-builtin,zip-builtin-not-iterating,intern-builtin,unichr-builtin,reduce-builtin,standarderror-builtin,unicode-builtin,xrange-builtin,coerce-method,delslice-method,getslice-method,setslice-method,input-builtin,round-builtin,hex-method,nonzero-method,map-builtin-not-iterating,no-member,fixme,anomalous-backslash-in-string,too-many-public-methods,no-self-use
+disable=import-star-module-level,old-octal-literal,oct-method,print-statement,unpacking-in-except,parameter-unpacking,backtick,old-raise-syntax,old-ne-operator,long-suffix,dict-view-method,dict-iter-method,metaclass-assignment,next-method-called,raising-string,indexing-exception,raw_input-builtin,long-builtin,file-builtin,execfile-builtin,coerce-builtin,cmp-builtin,buffer-builtin,basestring-builtin,apply-builtin,filter-builtin-not-iterating,using-cmp-argument,useless-suppression,range-builtin-not-iterating,suppressed-message,no-absolute-import,old-division,cmp-method,reload-builtin,zip-builtin-not-iterating,intern-builtin,unichr-builtin,reduce-builtin,standarderror-builtin,unicode-builtin,xrange-builtin,coerce-method,delslice-method,getslice-method,setslice-method,input-builtin,round-builtin,hex-method,nonzero-method,map-builtin-not-iterating,no-member,fixme,anomalous-backslash-in-string,too-many-public-methods,no-self-use,useless-object-inheritance
 
 
 [REPORTS]

lib/gamtools/cosegregation.py

@@ -45,7 +45,6 @@ class InvalidDataError(Exception):
     """
     Exception raised if segregation data contains anything other than 0s and 1s.
     """
-    pass
 
 
 def regions_are_valid(regions):

lib/gamtools/qc/pass_qc.py

@@ -96,8 +96,6 @@ class QcParamError(Exception):
     Exception to be raised if the QC Parameters file is malformed.
     """
 
-    pass
-
 
 def do_comparison(left_str, operator, right_str, stats_df):
     """

lib/gamtools/segregation.py

@@ -66,7 +66,6 @@
 
 class InvalidChromError(Exception):
     """Exception to be raised when an invalid chromosome is specified"""
-    pass
 
 
 def open_segregation(path_or_buffer):

tox.ini

@@ -16,11 +16,15 @@ commands =
 [testenv:pylint]
 deps =
     pylint
+basepython =
+    python3.6
 commands =
     pylint gamtools --rcfile={toxinidir}/.pylintrc
 
 [testenv:docs]
 changedir=docs
+basepython =
+    python3.6
 deps=
     sphinx
     sphinx_rtd_theme