Source local config

Addresses #9, "Add local config override file". As stated there, this
needs to have distro/package configs in bash associative arrays to
work for overriding package and distro configuration; e.g.

    DISTRO_MIRROR[jessie]=http://http.us.debian.org/debian

.gitignore

@@ -10,3 +10,5 @@
 /docker/
 # apt package repository
 /repo/
+# local config
+/local-config.sh

local-config-example.sh

@@ -0,0 +1,18 @@
+# dbuild local configuration example
+#
+# Copy this file to `local-config.sh` and customize for your site
+#
+# The below examples are intended for many use cases; see
+# `scripts/base-config.sh`, `scripts/packages/*.sh` and
+# `scripts/distro/*.sh` for more variables to customize
+
+# http/https proxy for package downloads
+#HTTP_PROXY=http://192.168.0.42:3128
+
+# Whether to always allocate a tty in Docker (true/false)
+#
+# A bug in Docker pre-1.1.1 prevents command exit status from the
+# `docker run` command when a tty is allocated. Set to `false` if you
+# need exit status from Docker.
+#DOCKER_ALWAYS_ALLOCATE_TTY=true
+

scripts/init-cli.sh

@@ -204,6 +204,11 @@ if test -n "$PACKAGE"; then
     . $PACKAGE_CONFIG_DIR/$PACKAGE.sh
 fi
 
+# Source optional config override file
+if test -f $BASE_DIR/local-config.sh; then
+    debug "    Sourcing local config"
+    . $BASE_DIR/local-config.sh
+fi
 
 # Debug
 ! $DDEBUG || set -x