let's try to do some Travis-CI with shellcheck

.travis.yml

@@ -0,0 +1,18 @@
+language: bash
+
+# Use container-based infrastructure for quicker build start-up
+sudo: false
+
+addons:
+  apt:
+    sources:
+    - debian-sid
+    packages:
+    - shellcheck
+
+script:
+  - shellcheck duplicity-backup.sh
+  - shellcheck -e SC2034 duplicity-backup.conf.example
+
+matrix:
+  fast_finish: true