npm outdated --parseable fix

Previous `--parseable` implementation was not displaying any relevant information about versions without combining `--long`. It might have been just copied from `npm ls`. Anyway, it seems `--long` has no use now so I removed it. Also added missing `latest` version info in parseable string. (... I guess no one was using `--parseable` before)

At a glance:
(previously) `npm outdated --parseable` -> `/.../node_modules/a`
(previously) `npm outdated --parseable --long` -> `/.../node_modules/a:a@(want):a@(has)`
(fixed) `npm outdated --parseable --long` -> `/.../node_modules/a:a@(want):a@(has):a@(latest)`

Plus: I removed the comment about `--json`(67 line) since it's already been implemented.