Get user creation working

.SRCINFO

@@ -1,10 +1,11 @@
 # Generated by mksrcinfo v8
-# Tue Apr 11 13:16:53 UTC 2017
+# Tue Apr 11 13:52:41 UTC 2017
 pkgbase = mastodon
 	pkgdesc = A GNU Social-compatible microblogging server
 	pkgver = 1.1.1
 	pkgrel = 0.1
 	url = https://mastodon.social
+	install = mastodon.install
 	arch = i686
 	arch = x86_64
 	license = AGPL-3.0

PKGBUILD

@@ -10,11 +10,7 @@ license=('AGPL-3.0')
 conflicts=("${pkgname}-git" "${pkgname}-docker" "${pkgname}-docker-git")
 source=("https://github.com/tootsuite/${pkgname}/archive/v${pkgver}.tar.gz")
 sha256sums=('e5b394a764710facb5830b7fad54a714aa08920017e6ecd02145bcbf70c5cded')
+install=mastodon.install
 _user=mastodon
-_homedir="/var/lib/${pkgname}"
-_shell="/bin/false"
-
-post_install() {
-    getent group ${_user} > /dev/null || groupadd ${_user} > /dev/null
-    getent passwd ${_user} > /dev/null || useradd -d ${_homedir} -g ${_user} -s ${_shell} ${_user} > /dev/null
-}
+_homedir=/var/lib/mastodon
+_shell=/bin/false

mastodon.install

@@ -0,0 +1,8 @@
+_user=mastodon
+_homedir=/var/lib/mastodon
+_shell=/bin/false
+
+post_install() {
+    getent group ${_user} > /dev/null || groupadd ${_user} > /dev/null
+    getent passwd ${_user} > /dev/null || useradd -d ${_homedir} -g ${_user} -s ${_shell} ${_user} > /dev/null
+}