fix url concat in command(), update forum link

[Pack3tL0ss]

base.py command() would result in an invalid url ...arubanetworks.comconfiguration/...
When called via update template. configuration.py update_template() uses urls.urlJoin which results in a
the url suffix with no leading "/"

The existing get_url method seemed like the best way to handle it.

commit also includes removal of trailing white-space
Update airheads forum url (forum backend recently changed)

[karthikeyan-dhandapani]

Thanks @Pack3tL0ss for your contribution. Please submit to the development branch next time. I will update the contribution guidelines about submission to the development as well.

[Pack3tL0ss]

Thanks! I'll submit to dev next time. and yes this is Wade