migrate from istanbul to nyc

Author: vahidalizad

.gitignore

@@ -12,6 +12,7 @@ pids
 lib-cov
 
 # Coverage directory used by tools like istanbul
+.nyc_output
 coverage
 
 # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)

.nycrc

@@ -0,0 +1,5 @@
+{
+  "reportDir": "./coverage",
+  "reporter": ["lcov", "text"],
+  "extension": [".js", ".ts"]
+}