Add a test for text MIME type. Note that various tests

may fail based on the version of LWP installed.

t/Macro/FetchMimeType.t

@@ -20,6 +20,11 @@ use Test::More; # increment this value for each test you create
 my $session = WebGUI::Test->session;
 
 my @testSets = (
+	{
+		input => 'webgui.txt',
+		output => 'text/plain',
+		comment => q|text|,
+	},
 	{
 		input => 'plainblack.gif',
 		output => 'image/gif',