attachments: fixing behavior where the edit button has not been shown correctly. Adding first specs for document upload scenario for a closed group.
group member list export: making specs sensitive.

The specs have not been checking all list export types due to a syntax
mistake.

Always use `[‚foo‘, ‚bar‘].each { |str| … }` and do not use `for str in
[‚foo‘, ‚bar‘]`!

As a result, the specs have not been sensitive to an issue where the
birthday list could not be created due to a missing date of birth.

The spec is now fixed.
user#age: fixing the age method for users without date of birth.

This has caused problems during group member list exports.
excluding some upload specs from travis, since they do not support file uploads.
page#show: fixing an issue where the page caused an error when current_user was nil.
fixing random spec issues.