Add the ability for chunk morphs to specify devices

Within a linux-user-chroot, we do not want to allow arbitrary code to
create device nodes, but still want it to be possible to create a device
node. This commit creates and handles the 'devices' field in a chunk
morphology, which takes:

* filename. A string, e.g. "/dev/null"
* uid. The ID of the user the file belongs to, e.g. 0 for root.
* gid. The ID of the group the file belongs to, e.g. 0 for root.
* type. A string of either 'c' for a character device or 'b' for a block
  device.
* major. The device's major number.
* minor. The device's minor number.
* permissions. A string of the octal number that would be passed to chmod
  e.g. '0777'

1 files changed, 1 insertions, 0 deletions

diff --git a/morphlib/plugins/branch_and_merge_plugin.py b/morphlib/plugins/branch_and_merge_plugin.py
index f9595f98..cbc41acf 100644
--- a/morphlib/plugins/branch_and_merge_plugin.py
+++ b/morphlib/plugins/branch_and_merge_plugin.py
@@ -348,6 +348,7 @@ class BranchAndMergePlugin(cliapp.Plugin):
                 'install-commands',
                 'max-jobs',
                 'chunks',
+                'devices',
             ]
         }