Fix branches/compare butten to directly diff to default branch
 Merge branch 'request/branch_compare' into 'master'

Fix for compare button within branches dialog

For the button Compare within the Branches screen ( https://gitlab.com/gitlab-org/gitlab-ce/branches ) beside a branch "foo"

Old behavior:
Will redirect to the compare page that is defaulted to comparison for branch "foo" <--> "foo"

New behavior:
Will redirect and trigger compare page of branch "default" <--> "foo"
Remove of button beside default branch
Merge branch 'master' of gitlab.com:gitlab-org/gitlab-ce