Merge lp://staging/~debian-janitor/friendly-recovery/lintian-fixes into lp://staging/~ubuntu-core-dev/friendly-recovery/ubuntu

Fix lintian issues: Add missing build dependency on dh addon., Bump debhelper from old 10 to 12., Set debhelper-compat version in Build-Depends., Trim trailing whitespace., Use secure URI in Vcs control header Vcs-Bzr.

Fix some issues reported by lintian
* Trim trailing whitespace. (file-contains-trailing-whitespace)
* Add missing build dependency on dh addon. (missing-build-dependency-for-dh-addon)
* Bump debhelper from old 10 to 12. (package-uses-old-debhelper-compat-version)
* Set debhelper-compat version in Build-Depends. (uses-debhelper-compat-file)
* Use secure URI in Vcs control header Vcs-Bzr. (vcs-field-uses-insecure-uri)

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