Improve gitignore (#21)

* Add comments to .gitignore

Helps to identify the reason why each item is ignored and also
ends up better structured.

* .gitignore: Add thumbnails, vim and intellij IDE files

- thumbnails: autogenerated OS icons
- vim and intellij: two of the most used IDEs

Author: allaudet

.gitignore

@@ -1,6 +1,25 @@
+# Logs
 *.log
-node_modules
+
+# Node
+node_modules/
+
+# Project specific
 config/database.js
+
+# Unit test / coverage reports
 coverage/
 .nyc_output
-.DS_STORE
+
+# OS auto-generated files
+.DS_Store
+._*
+
+
+# Vim
+*~
+*.swp
+*.swo
+
+# IDE files
+.idea/