Add coverage and code quality badges.

concatenate_coverage

@@ -0,0 +1,12 @@
+#!/bin/bash
+# Concatenate a list of coverage reports
+# Usage: concatenate_coverage <out> [[test] ...]
+
+output_file=$1
+shift
+cat $1 > $output_file
+shift
+
+for f in $@ ; do
+    tail -n +2 $f >> $output_file
+done