Fix select fields regression on master backlog/taskboard after merging #942.

Added check to ensure default select value does not override values of existing stories/tasks.
Change travis to use RM 2.3.2

Redmine has pinned nokogiri at '< 1.6.0'. Backlogs does the same for now.
fix typos in spanish translation
Merge pull request #947 from dmoreno/patch-1

fix typos in spanish translation
added tests for the default story tracker
Merge remote-tracking branch 'stefan-langenmaier/27130-invert-story-bug'
Merge remote-tracking branch 'origin/master'
Collect release_id information from parent issues to get the correct sum of hours for the time report view in redmine.

This is necessary as only stories have the release_id set. Thus time entries logged on tasks need to inherit release_id
from parent issue.
Deal with non-existing issue id's in changelog
v1.0.4
added some tests on the taskboard
Issue 27131: fix french translation
enhanced the taskboard tests for assigned users
Merge pull request #950 from stefan-langenmaier/27131-french-translation-fixes

Issue 27131: fix french translation
Remove issues assigned to release from product backlog query on issues tab. (#951)
Allow other tests to create stories without specifying tracker.
Change master backlog/taskboard tests related to default story tracker and other select fields into tests using full javascript stack.
Merge branch '27130-invert-story-bug'
Utilize SQL for fetching release/sprint shared to projects. Huge improvement for #868 and improvement on total loading time for #931 and #938.
Optimized SQL for droppable sprints/releases on master backlog. (Big performance improvement related to #931 and #938)