net/: refactor cfg templates

Adopt "foreach" and "common_" features and generally take in the improved
templates as used at 35c3.

If your config file relies on the tmpl_std that is now removed, you can locally
resurrect it with

  git checkout 2c6a55baa72de0e -- tmpl_std

but it's probably better to make a new copy of config_2g3g and insert your
local config there.

Change-Id: Ie6352c584c0fce57c617387160c285abf40a5f90
diff --git a/net/templates/common_logging b/net/templates/common_logging
new file mode 100644
index 0000000..57cf16e
--- /dev/null
+++ b/net/templates/common_logging
@@ -0,0 +1,8 @@
+ logging filter all 1
+ logging color 1
+ logging print level 1
+ logging print category 1
+ logging print category-hex 0
+ logging print file basename last
+ logging print extended-timestamp 1
+ logging level set-all debug