Improve calendar widget

See merge request !1453

Expose Link header in CORS Api calls

* cache user contributions for day
* ignore forks in calendar contribtuions

Refactor Repository to use new RepositoryCache class

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

Abstracts away the lower-level implementation details from the
Repository model.

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