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".
Accept our license agreement.
Add numbers.
Fix numbering by indenting.
Enable rack_attack by default.
Remove separate installation of charlock_holmes.
New API: create file in repo

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Specs for Create file API

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Improve message in email notifications
Removed Project#discover_default_branch since it not needed any more

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Allow closes/closed & fixes/fixed for automatic regex closing
Merge branch 'no_separate_gem' of /home/git/repositories/gitlab/gitlabhq
Merge branch 'ra_default' of /home/git/repositories/gitlab/gitlabhq
Fix minor errors/annoyances in email templates

There was some funny syntax in merge request email templates. There was a ! before
the merge request number when there probably should be a #. This may be some carry over
from markdown but should not be in email templates.  There were also some capitalization
discrepancies among the subject lines. For those OCD people out there I standardized the
capitalization. :)
Add specs for Email confirmation

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'contribution-license-agreement' of /home/git/repositories/gitlab/gitlabhq
Make sure private_token for API is a string

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge pull request #4795 from bke-drewb/issue-4769

Issue-4769 - Unable to update case of label
Merge pull request #5571 from bke-drewb/email

Fix minor errors/annoyances in email templates
Add docs for create file API

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>