Serve index file when path is '/'.

[iphoting]

Currently, Vienna returns NotFound (404) when accessed with / path.

% rake test
Run options: --seed 27614

# Running:

..FF..

Finished in 0.036410s, 164.7899 runs/s, 302.1148 assertions/s.

  1) Failure:
Vienna::when requesting the root directory#test_0001_should serve the index path [spec.rb:21]:
--- expected
+++ actual
@@ -1 +1,2 @@
-"index"
+# encoding: ASCII-8BIT
+"404"


  2) Failure:
Vienna::when requesting the root directory#test_0002_should return a valid status code, that is 200: OK or 304: Not Modified [spec.rb:25]:
Expected [200, 304] to include 404.

6 runs, 11 assertions, 2 failures, 0 errors, 0 skips

Expected behaviour should be to return index.html instead of 404.html.

My fix passes:

% rake test
Run options: --seed 32465

# Running:

......

Finished in 0.020588s, 291.4319 runs/s, 534.2918 assertions/s.

6 runs, 11 assertions, 0 failures, 0 errors, 0 skips