contactrequestcontentview: improve ui

Change button style, icons and center the layout.

Change-Id: I2931017c8d9c0dcbe532a39dabd3cf182c7a3408
Reviewed-by: Philippe Gorley <philippe.gorley@savoirfairelinux.com>
diff --git a/pixmaps/reject.svg b/pixmaps/reject.svg
new file mode 100644
index 0000000..4bc46d3
--- /dev/null
+++ b/pixmaps/reject.svg
@@ -0,0 +1,4 @@
+<svg fill="#ffffff" height="24" viewBox="0 0 24 24" width="24" xmlns="http://www.w3.org/2000/svg">
+    <path d="M19 6.41L17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z"/>
+    <path d="M0 0h24v24H0z" fill="none"/>
+</svg>