no_bootstrap code was working backwards

This should address #3
--no-bootstrap will skip bootstrapping and the check for credentials
--bootstrap (or omitting it) will check if credentials are given and do a bootstrap.

<snip>
[frank@tom WindowsBaseImage]$ knife cs server create 'fb2013040201' --service 'cust-large-ha' --template 'MotherWindows2008R2x64EEv1' --defaults --disable-editing --no-bootstrap --no-public-ip --cloudstack-project 'windowsbase'  -V -V
DEBUG: Validate hostname and options
INFO: Creating instance with
        service : cust-large-ha
        template : MotherWindows2008R2x64EEv1
        zone :
        project: windowsbase
        network: []

Waiting for Server to be created......

Name: fb2013040201
Public IP: 10.1.1.233
[frank@tom WindowsBaseImage]$
</snip>