Improvements to LDAP::User model

* method #changed? also tracks changes of identites (fixes issue with email mapping)
* find ldap identity before initialize one

Fixes #1946

See merge request !1452

* method #changed? also tracks changes of identites (fixes issue with email mapping)
* find ldap identity before initialize one

User contribution calendar via ajax

See merge request !1451

Bump GitLab for Docker to version 7.7.1

See merge request !321

Ability to clone project using oauth2 token

See merge request !1447

UX improvements (Implement lessons from user testing)

* add link to permissions help page from new project/group member form
* Improve UX for widget if merge request can not be merged
* Improve wording for fork project page

See merge request !1448

Small css improvements

See merge request !1450

Create gitlab internal issue service

Part of #1908

Create a default gitlab issue tracker service which will replace having issue tracker fields for project.

See merge request !1449

Update semantic-ui-sass to 1.8

Saner LDAP defaults

I have the impression that most people use LDAP servers listening
on port 389, without encryption. If we make that the default we
give people a smoother ride setting up GitLab.

See merge request !1446