Hide the Rebase button

Permanently hide the Rebase button so rebasing a change is never
possible from the web UI. Set following value in 'gerrit.config'
to make this happen:

[gerrit]
    hiderebase = true

If this value is not set (or is false) the default Gerrit way is on.
Then the change owner and submitters can always rebase changes in the
web UI (even without having the Rebase access right assigned).

Task-number: QTQAINFRA-848
Change-Id: I6e26f6ab5e88d0446d6bcb5081e74976f16cc5d0
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Ismo Haataja <ismo.haataja@digia.com>
Fix unstaging a STAGING change

Allowed unstaging also from STAGING state in database update function.
Without this, state was not changed at all even though "Unstaged" change
message was posted. Because change was not moved to NEW state as expected,
this also caused an error message complaining about incorrect state.

Task-number: QTQAINFRA-857
Change-Id: Iea359597584991fb6da17a72cf0c400970cafda6
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Ismo Haataja <ismo.haataja@digia.com>
Show review scores for staged changes

Review scores (aka submit records) where not fetched because the
function doing this (getSubmitRecords) utilizes 'canSubmit' function
that returns error for a change in STAGING or STAGED state. Added new
parameter (allowStaged) to function interface to allow bypassing this
check and get review scores fetched.

Task-number: QTQAINFRA-859
Change-Id: I48c06e6a5833e762529efb305ef93182d4202572
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Ismo Haataja <ismo.haataja@digia.com>