Core::Id: Remove some explicit casts to Core::Id

Change-Id: Ibe505c8331f7d1280fdb8784a00321742f5d94cb
Reviewed-by: hjk <hjk121@nokiamail.com>
Apply 'static' pattern to VcsManager

Adapt user and surrounding code.

Change-Id: Id2648f82a9cbbd0ad0bfb91f6958b8cee7ea29cc
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>