oomph: Fix redmine API key query.
* Undeclared variables shall not be used with oomph since they are demanded every time eclipse is started. * Instead, use the "key" variable directly to demand the API key during the initial setup steps. * The "PASSWORD" cannot be used since mylyn requires the API key in clear text and stores it as such. Thus, we are doomed to use the "STRING" variable type. Issue-Ref: 3406 Signed-off-by: Alexander Diewald <firstname.lastname@example.org>