Fix indenting, break long lines

Tabs were used in the example bash script. Also break some long lines.
Fix configuration name

Use CONFIGURATION variable for the puppet:install task.
example_xen.bash is an executable script

Add the sheebang, parameter parsing, so that example_xen.bash could be
executed as a script easily. The script also injects the xenserver
password to the puppet manifest.
Merge pull request #29 from matelakat/xenfixes

Xenfixes