Issue-4769 - Unable to update case of label

Labels are saved in the database with the case they were originally created with.
Before this change if a user created a label with the same text but different case
the label would use the original case and no new label would be created in the
database. With this change, labels are now case-sensitive.

Steps to test:

1. Before this change, create a new issue with a new label "FIxMe"
2. Edit the issue and change the label to "FixMe"
3. Note that the label reverted to "FIxMe"
4. Apply this change
5. Edit the issue again and change the label to "FixMe"
Note that the new case was preserved. If you also look in the database in the "tags" table you will see that both labels are present - "FIxMe" and "FixMe".
Read configuration variable file if it is present
Fix Markdown help page: escape file link syntax example to leave it unprocessed
Accept our license agreement.
Add numbers.
Fix numbering by indenting.
Preselect the current issue tracker with selected="selected"

The previous behavior was, that the first element of the select was
preselected, thus upon saving the project, the previous selected could
be overwritten.
Use gitlab-shell 1.7.4
Fixes 500 error when user types in wrong group name.
Run tests in parallel on travis
Add security warnings to update docs
Bump gitlab-shell in 5.4 and 6.2
Add 5.1-to-5.4 update path
Clarify upgrade steps
Add security update info to 6.0-to-6.2.md
Support -ms-linear-gradient style for IE10+
When looking up a user by DN, use single scope

The blocked? method is used to check whether a user exists in LDAP. Prior to this change, if the LDAP server had more objects below the one pointed to by the DN, those objects would also be picked up by the search, causing the method to determine the user should be blocked.

One case where this can happen is when using Active Directory and a user have a mobile phone assigned. In this case, Exchange will add an entry called ExchangeActiveSyncDevices under the users entry. The user-visible behaviour is then that a user loses Gitlab access when he enables a mobile device.

This fix sets the search scope to BaseObject in order to ensure that only the user itself is returned.
Merge branch 'gitlab_shell_174_for_master' of /home/git/repositories/gitlab/gitlabhq
Merge pull request #5519 from zzet/patch-3

Run tests in parallel on travis
Merge pull request #5512 from jhollingsworth/feature/missing-group-500-fix

Fixes 500 error when user types in wrong group name.