hypervisor: manage nova shell

To enable live-migration & resize feature, nova user needs to run
/bin/bash shell (need from libvirt).
By default packaging set /bin/nologin for some security reasons.
Let's bring more flexibility and let the end user to set another shell
for Nova on Hypervisor nodes.
Defaults to false to keep default packaging configuration.

Close #600

spec/classes/cloud_compute_hypervisor_spec.rb

@@ -81,6 +81,7 @@ describe 'cloud::compute::hypervisor' do
         :ks_spice_public_host                 => '10.0.0.2',
         :vm_rbd                               => false,
         :volume_rbd                           => false,
+        :nova_shell                           => false,
         :ks_nova_public_host                  => '10.0.0.1' }
     end
 
@@ -224,6 +225,10 @@ describe 'cloud::compute::hypervisor' do
       is_expected.to contain_class('ceilometer::agent::compute')
     end
 
+    it 'do not configure nova shell' do
+      is_expected.not_to contain_user('nova')
+    end
+
     it 'should not configure nova-compute for RBD backend' do
       is_expected.not_to contain_nova_config('libvirt/rbd_user').with('value' => 'cinder')
       is_expected.not_to contain_nova_config('libvirt/images_type').with('value' => 'rbd')
@@ -320,6 +325,21 @@ describe 'cloud::compute::hypervisor' do
       end
     end
 
+    context 'when managing nova shell' do
+      before :each do
+        params.merge!( :nova_shell => '/bin/bash')
+      end
+      it 'ensure nova shell is configured by Puppet' do
+        is_expected.to contain_user('nova').with(
+          :ensure     => 'present',
+          :system     => true,
+          :home       => '/var/lib/nova',
+          :managehome => false,
+          :shell      => '/bin/bash'
+        )
+      end
+    end
+
     context 'with RBD backend for instances and volumes on Debian plaforms' do
       before :each do
         facts.merge!( :osfamily => 'Debian',