Import Debian changes 1.8.6-1

network-manager-l2tp (1.8.6-1) experimental; urgency=medium
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  * New upstream release.
  * Update Source and add Upstream-Contact in debian/copyright
  * Remove unused dh_makeshlibs override
  * Bump Standards-Version to 4.5.1
  * Bump watch file version to 4
  * Bump debhelper to 13.
  * Use /usr/share/metainfo for AppData files
  * Remove redundant patch to move D-Bus policy file
  * Apply patch to remove GPLv2/OpenSSL license conflict in README.md