increase wordwrap width to 90

fixes display of long 'wp core config' example
Turn `validate_role()` into a more helpful method and apply it in more places
Also validate `wp user remove-role`
`$role` can be empty for `wp user generate`
Add some tests for error conditions with roles
Changed dump into export.
Merge pull request #1056 from clemens-tolboom/feature/dump-should-be-export

Changed dump into export.
show error when invalid format is passed
move --format=ids handling to individual commands
Merge pull request #1058 from wp-cli/format-ids

move --format=ids handling to individual commands
test that failure is due to expected error
Merge pull request #1053 from wp-cli/valid-role

Turn `validate_role()` into a more helpful method and apply it in more places