Add install and upgrade information for CentOS/RHEL and Ubuntu
Merge pull request #2166 from opf/hotfix/update_docs_supported_distros

Add install and upgrade information for CentOS/RHEL and Ubuntu
Make the installation prerequisites more consistent with regard to CentOS/RHEL, Fedora and Ubuntu
formatting of bullets
rewriting i18n tests as specs
one class variable less
Merge pull request #2165 from opf/hotfix/i18n_testing_as_specs
Fix the URL for the stable branch of Fedora 20 packager
Merge pull request #2172 from lindenthal/release/4.0

Fix the URL for the stable branch of Fedora 20 packager
Correct API experimental's users path
Merge pull request #2177 from opf/hotfix/17173_user_related_wp_filters_are_inactive

17173 User related WP filters are inactive
Consider width limitation in wiki
Merge pull request #2176 from opf/hotfix/16959_timelines_macro_does_not_have_sufficient_width

16959 timelines macro does not have sufficient width
Merge branch 'release/4.0' into dev

Conflicts:
	app/assets/javascripts/angular/timelines/directives/timeline-container-directive.js
	lib/redmine/i18n.rb
	spec/lib/redmine/i18n_spec.rb
Merge pull request #2188 from opf/feature/merge_release_4_into_dev