Removed unused exceptions from error.py
Moved definition of WicError to lib/wic/__init__.py
(From OE-Core rev: 15442d072bb6d93bd9b941726f93262503053da5)
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>