Update to 3.1.1

Changhelog:
== 2015-09-20 v3.1.1

* Feature #11253: Total time spent from subtasks on the issue list
* Feature #20688: Add Total estimated hours column on issue list
* Feature #20738: Upgrade Rails 4.2.4
* Defect #19577: Open redirect vulnerability
* Defect #20761: Fix typo of Japanese translation for notice_gantt_chart_truncated
* Defect #20427: Cannot create a custom query visibility is "to these roles only"
* Defect #20454: Mail handler: unwanted assignment to a group occurs
* Defect #20278: Wrong syntax for resizing inline images will throw a 500 error
* Defect #20401: "Spent time" panel: columns not wrapping
* Defect #20407: Monospace font-family values are differ between application.css and scm.css
* Defect #20456: 3.1-stable/3.1.0: missing commits (omitted from being merged from trunk)
* Defect #20466: Broken email notification layout in Outlook
* Defect #20490: WARNING: Can't mass-assign protected attributes for User
* Defect #20633: Help cursor showing up since r14154
* Patch #20293: Russian translation for 2.6-stable
* Patch #20294: Russian translation for 2.6-stable
* Patch #20408: Turkish translation for 2.6-stable
* Patch #20557: Czech translation for 2.6-stable
* Patch #20735: Markdown: Upgrade redcarpet gem to 3.3 (ruby 1.9 and higher)
* Patch #20745: Portuguese translation for 2.6-stable
* Patch #20512: Project.copy_from deletes enabled_modules on source
* Patch #20737: Czech translation for 3.0-stable
* Patch #20746: Portuguese translation for 3.0-stable
* Patch #20243: Use https links instead of http links in ApplicationHelper#avatar_edit_link and Redmine::Info class methods
* Patch #20410: Turkish translation for 3.1-stable
* Patch #20452: Czech localisation update
* Patch #20731: Change Japanese translation for "spent time"
* Patch #20747: Portuguese translation for 3.1-stable

(ryoon)