snap-packaging for gitea (#2568)

* Modify tbraeutigam/gogs-snap for gitea

* Fix building on 16.04 (manually build go-bindata).
-> add _source.tar.bz2 to .gitignore (used by snapcraft cleanbuild)

* Streamline Snap packaging:
 - Take advantage of install-hooks (snapd 2.27)
 - Use snapctl configuration storage for unchanging values

* Move to using Snap Hooks for configuration

* Missed re-adding daemon statement

* Fix two warnings from Codacy.

snap/helpers/simple_launcher.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+if ! env | grep -q root; then
+  echo "
+   +----------------------------------------+
+   | You are not running gitea as root.     |
+   | This is required for the snap package. |
+   | Please re-run as root.                 |
+   +----------------------------------------+
+"
+  $SNAP/gitea/gitea --help
+  exit 1
+fi
+
+# Set usernames for gitea
+export USERNAME=root
+export USER=root
+
+export GITEA_WORK_DIR=$(snapctl get gitea.snap.workdir)
+export GITEA_CUSTOM=$(snapctl get gitea.snap.custom)
+
+$SNAP/bin/gconfig save
+cd $SNAP/gitea; ./gitea $@