Add (expert) setting for configuring instance_user

https://bugzilla.novell.com/show_bug.cgi?id=871131
Generate an auth encryption key of at least 32 chars

It needs that many characters for seeding the Crypto routines.
add travis testing support
Merge pull request #80 from dirkmueller/master

Generate an auth encryption key of at least 32 chars
Merge pull request #79 from dirkmueller/instance_user

Add (expert) setting for configuring instance_user
Add optional crowbar-applied boolean attribute to schema

Set it to false by default in the json and update proposal schema
version to 3.