if-branch context for version

[tonyhffong]

Reminder to add branch context for if statement so we don't get too much noises, such as

if VERSION < v"0.3-"
   # lint should reference this constraints so we don't get false positives due to version differences
end

[tonyhffong]

Separate type-context in a different issue since VERSION context is more urgent and easier to implement (I think).

[tonyhffong]

This is required so that we can generate sensible lint messages for this issue: #57