Update git submodules

* Update docs/submodules/barometer from branch 'master'
  - cleanup: remove fuel plugin since fuel@opnfv uses mcp

    Change-Id: I1c745106c1db5e69ba698d9076ae6c707dbc37b7
    Signed-off-by: Guo Ruijing <ruijing.guo@intel.com>

diff --git a/docs/submodules/barometer b/docs/submodules/barometer
index e81d42e..7dcda31 160000 (submodule)
--- a/docs/submodules/barometer
+++ b/docs/submodules/barometer
@@ -1 +1 @@
-Subproject commit e81d42edd4199d13d779753d1969f23ba74c98da
+Subproject commit 7dcda31fe01f5fe910033a0ff97eb1ba795ee680