Make diff colors brighter

Use the same colors as gitweb for add and delete lines,
and a brighter blue for the hunk header.

Bug: http://code.google.com/p/gitiles/issues/detail?id=9
Change-Id: I87ad387c03155770282cdf676b62cb59422800d8

gitiles-servlet/src/main/resources/com/google/gitiles/static/gitiles.css

diff --git a/gitiles-servlet/src/main/resources/com/google/gitiles/static/gitiles.css b/gitiles-servlet/src/main/resources/com/google/gitiles/static/gitiles.css
index 94460ab..851e9bf 100644
--- a/gitiles-servlet/src/main/resources/com/google/gitiles/static/gitiles.css
+++ b/gitiles-servlet/src/main/resources/com/google/gitiles/static/gitiles.css
@@ -301,13 +301,13 @@
   border-bottom: #ddd solid 1px; /* BORDER */
 }
 .diff-unified .h {
-  color: darkblue;
+  color: #0000cc;
 }
 .diff-unified .d {
-  color: darkred;
+  color: #cc0000;
 }
 .diff-unified .i {
-  color: darkgreen;
+  color: #008800;
 }