[sushi] release: prepare for 3.28.0

[Cosimo Cecchi <cosimoc src gnome org>]

commit 0c14d738e508f8c7e0959221d3f8623c5f9b72c1
Author: Cosimo Cecchi <cosimo endlessm com>
Date:   Wed Apr 18 18:38:04 2018 -0700

    release: prepare for 3.28.0

 NEWS         |    7 +++++++
 configure.ac |    2 +-
 2 files changed, 8 insertions(+), 1 deletions(-)
---
diff --git a/NEWS b/NEWS
index 9656a0c..16b2d5c 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,10 @@
+3.28.0
+======
+
+- Add support for GIF animations (Princeton Ferro)
+- Use LibreOffice directly instead of unoconv (Robert McQueen)
+- Prefer LibreOffice from flatpak when installed (Robert McQueen)
+
 3.24.0
 ======
 
diff --git a/configure.ac b/configure.ac
index 617685c..5667565 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,6 +1,6 @@
 dnl -*- mode: m4 -*-
 AC_PREREQ(2.63)
-AC_INIT([sushi],[3.24.0],[],[sushi])
+AC_INIT([sushi],[3.28.0],[],[sushi])
 
 AC_CONFIG_HEADERS([config/config.h])
 AC_CONFIG_SRCDIR([src/main.c])