Clean up views which use @project.nil? or @project.module_enabled?(:gtt)

[sanak]

Problem
Related with #268, I noticed that @project.nil? or @project.module_enabled?(:gtt) is used in several views.

• Search query: https://github.com/search?q=repo%3Agtt-project%2Fredmine_gtt+%22%40project.nil%3F+or+%40project.module_enabled%3F%28%3Agtt%29%22&type=code
  • app/views/
    • issues/index/_geojson.html.erb
    • issues/show/_geojson.html.erb
    • issues/show/_map.html.erb
    • projects/show/_map.html.erb
    • projects/show/_other_formats.html.erb
    • redmine_gtt/hooks/_view_issues_form_details_top.html.erb
    • users/show/_other_formats.html.erb

But, those need to be reviewed.
(For example, above list's last users/show/_other_formats.html.erb should not use @project instance variable.)