avoid use of /dev/disk/by-id in VirtualBox

/dev/disk/by-id is unstable under VirtualBox so we don't want to rely on
it.
Merge pull request #305 from aspiers/virtualbox-disk-by-id

avoid use of /dev/disk/by-id in VirtualBox
add travis testing support
Add optional crowbar-applied boolean attribute to schema

We add a crowbar applied attribute to mark the proposal as applied after
the chef run. This allows the UI to show that the current form of the
proposal has been 'applied' successfully (i.e. chef-client completed the
run w/ success) and that the proposal was not modified after that.

Update the proposal_schema_revision, so we can add the attribute to
schema for ('3rd party') barclamps that currently do not have it.

Refs: crowbar/crowbar#2044 (which adds this attribute to barclamps which
lack it), crowbar/barclamp-crowbar#1068 (which marks the proposals as
applied) and https://bugzilla.novell.com/show_bug.cgi?id=877486
Merge branch 'release/roxy/master' into merge-roxy
Merge pull request #316 from dirkmueller/master

add travis testing support
Merge pull request #317 from bkutil/add_applied_attribute

Add optional crowbar-applied boolean attribute to schema
Merge pull request #318 from vuntz/merge-roxy

Merge roxy branch into master
crowbar_join.suse: Remember reboot request

Remember reboot request so crowbar can wait until the reboot finished.
This is done in crowbars run_remote_chef_client() function. The newly added
start handler resets the reboot state.

https://bugzilla.novell.com/show_bug.cgi?id=878012
Disable probing of network interfaces

provides a significant speedup on running sudo on a larger
neutron deployment.

see http://www.sudo.ws/pipermail/sudo-workers/2014-January/000835.html
Merge pull request #320 from toabctl/remember-reboot

crowbar_join.suse: Remember reboot request
add zypper no-gpg-checks flag
Merge pull request #321 from MaximilianMeister/no-gpg-checks-option

add zypper no-gpg-checks flag
crowbar_join.suse: Always install chef handlers

Install chef reboot handlers also if /etc/chef/client.rb is
already available.
crowbar_join.suse: Remember time before reboot

Store seconds since epoch before reboot in
node[:crowbar_wall][:wait_for_reboot_requesttime] and reset the variable with
the reboot reset handler. The variable can be used to verify that a
reboot already happened.
Merge pull request #322 from toabctl/reboot-handler-upgrade

crowbar_join.suse: Always install chef handlers
Reflect latest changes on UEFI ohai plugin
Merge pull request #323 from tboerger/feature/uefi-fix

Reflect latest changes on UEFI ohai plugin
crowbar_join.suse: Reset reboot flag after reboot

Currently we reset node[:crowbar_wall][:wait_for_reboot] always before a
chef-client run. That doesn't work if there's another chef-client run
before the reboot happens.
Add a check which compares the stored time when the reboot was requested
and the time the node was booted to verify that the reboot finished.
Fixed a condition where uefi is not defined