Avoid unnecessary "if not"
string interpolation is preferred over concatenation

Please refer to https://github.com/bbatsov/ruby-style-guide
Favor "unless" over "if" for negative conditions

Please refer to https://github.com/bbatsov/ruby-style-guide
Fix comments
Do something for the shut-everything-up event handling practice
Better describe the problem
Merge pull request #1 from wchen-r7/pr3488_fix

More cosmetic fixes for enum_services