add .coverage configuration

.coverage

@@ -0,0 +1 @@
+!coverage.py: This is a private format, don't read it directly!{"lines":{"/Users/Pingjun/Pingjun/CPath/tissueloc/test/test_load_slide.py":[3,7,8,9],"/Users/Pingjun/Pingjun/CPath/tissueloc/test/test_locate_tissue.py":[3,4,5,6,7,9,10,11,14,15,16,18,19,20,21,22,23,26,27,29,30,32,33,34,36,37,39,40,41,43,44,45,46],"/Users/Pingjun/Pingjun/CPath/tissueloc/tissueloc/__init__.py":[3,5,7,8,10,11],"/Users/Pingjun/Pingjun/CPath/tissueloc/tissueloc/load_slide.py":[3,4,5,8,51],"/Users/Pingjun/Pingjun/CPath/tissueloc/tissueloc/locate_tissue.py":[3,4,5,6,7,9,12,28,53,70,89,112,45,46,48,50,66,68,84,86,101,102,103,105],"/Users/Pingjun/Pingjun/CPath/tissueloc/setup.py":[],"/Users/Pingjun/Pingjun/CPath/tissueloc/tissueloc/setup.py":[]}}