Explicitly set source encoding to utf-8

Running this module in my environment produces the following encoding error:  "SyntaxError: Non-ASCII character '\xc2' in file /home/jossy/.ansible/tmp/ansible-tmp-1416602106.74-253057196686273/vsphere on line 3, but no encoding declared; see http://python.org/dev/peps/pep-0263/ for details"

To fix this problem, I've added a line which declares the (utf-8) encoding explicitly.