gnt-instance: support no_PARAMETER value
gnt-instance: support no_PARAMETER value

Since parameters get set to False if a no_ is prefixed don't try to
interpret those boolean values, and pass them unchanged.

Reviewed-by: iustinp


dimara/ganeti,leshchevds/ganeti,apyrgio/ganeti,ganeti/ganeti,mbakke/ganeti,andir/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,leshchevds/ganeti,yiannist/ganeti,onponomarev/ganeti,yiannist/ganeti,bitemyapp/ganeti,ganeti-github-testing/ganeti-test-1,grnet/snf-ganeti,bitemyapp/ganeti,ganeti/ganeti,mbakke/ganeti,apyrgio/ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti,andir/ganeti,dimara/ganeti,yiannist/ganeti,leshchevds/ganeti,mbakke/ganeti,onponomarev/ganeti,apyrgio/snf-ganeti