modify factory_Wipe to fit into new flow (with factory_Verify)

The factory_Wipe now only depends on the factory_Verify test,
which can be assigned via unique_name in suite_Factory/test_list.
Ref: http://codereview.chromium.org/3180022/show

BUG=chrome-os-partner:827
TEST=manual

Change-Id: Icc9f84ee7aa0842de8075b4c94c79e0c9a7026bd

Review URL: http://codereview.chromium.org/3156047
3 files changed