Fix LICENCE file name and add AUTHORS file.

Change-Id: I8ce625ab430d39da199a605858dfe38cc3427351
Reviewed-on: http://gerrit.dmdirc.com/2651
Reviewed-by: Chris Smith <chris@dmdirc.com>
Automatic-Compile: DMDirc Build Manager

AUTHORS

@@ -0,0 +1,6 @@
+# This is the official list of DMDirc Developers for copyright purposes.
+Chris Smith <chris@dmdirc.com>
+Google Inc.
+Greg Holmes <greg@dmdirc.com>
+Shane McCormack <shane@dmdirc.com>
+Simon Mott <simon@dmdirc.com>