Merge branch 'release/4.0.0'

* release/4.0.0: (112 commits)
  Released v4.0.0
  Minor: Update MIGRATION Guide
  Updated error message
  Minor: formatting
  Updated MIGRATION Guide
  Updated CHANGELOG
  Add unit tests for v1 collection format
  Drop support for v1 collection format
  Removed incorrect cli test 🐛
  Fixed lint errors 👕
  fix(package): update postman-collection-transformer to version 2.6.2
  Fixed broken builds ✅
  Accounted for breaking changes in parse-gitignore v1.0.1
  fix(package): update commander to version 2.17.0
  Minor: fix README typo
  Update CLI unit tests
  Review changes
  Fix tests
  Cleanup options passed from CLI
  Update tests for `version` flag
  ...

.appveyor.yml

@@ -9,9 +9,9 @@ init:
 # environment variables
 environment:
   matrix:
-    - nodejs_version: "4"
     - nodejs_version: "6"
     - nodejs_version: "8"
+    - nodejs_version: "10"
 
 # scripts that run after cloning repository
 install: