Update git submodules

* Update charm-nova-compute from branch 'master'
  to 2f15742cb96e1e3dffe8bf375b0c584bbf0c2827
  - Fix build

    Summary:
    - Drop cliff
    - Add looseversion
    - Pin setuptools to allow keystoneauth1 get imported

    Change-Id: I6a3ef64e0f84e7936d894bed2127ea4c92f1c056
    Signed-off-by: Felipe Reyes <felipe.reyes@canonical.com>

diff --git a/charm-nova-compute b/charm-nova-compute
index 39b0065bd7fe4b97316a723b0e05ef0013aa6274..2f15742cb96e1e3dffe8bf375b0c584bbf0c2827 160000 (submodule)
--- a/charm-nova-compute
+++ b/charm-nova-compute
@@ -1 +1 @@
-Subproject commit 39b0065bd7fe4b97316a723b0e05ef0013aa6274
+Subproject commit 2f15742cb96e1e3dffe8bf375b0c584bbf0c2827