Use undercover to report coverage to coveralls.io

- Cask: Add undercover dependency for development
- dev/undercover.init: Do optional coverage reporting
- run-travis-ci.sh: Install Cask and dependencies

Cask

@@ -1 +1,8 @@
+(source gnu)
+(source melpa)
+
 (package-file "s.el")
+
+(development
+ (depends-on "undercover"))
+

dev/undercover-init.el

@@ -0,0 +1,2 @@
+(when (require 'undercover nil t)
+  (undercover "s.el"))

run-tests.sh

@@ -4,4 +4,4 @@ if [ -z "$EMACS" ] ; then
     EMACS="emacs"
 fi
 
-$EMACS -batch -l dev/ert.el -l dev/examples-to-tests.el -l s.el -l dev/examples.el -f ert-run-tests-batch-and-exit
+$EMACS -batch -l dev/ert.el -l dev/examples-to-tests.el -l dev/undercover-init.el -l s.el -l dev/examples.el -f ert-run-tests-batch-and-exit

run-travis-ci.sh

@@ -17,4 +17,12 @@ echo "EMACS =" $(which $EMACS)
 $EMACS --version
 echo
 
-exec ./run-tests.sh
+if [ "$EMACS" != "emacs23" ]; then
+  curl -fsSLo /tmp/cask-master.zip https://github.com/cask/cask/archive/master.zip
+  sudo unzip -qq -d /opt /tmp/cask-master.zip
+  sudo ln -sf /opt/cask-master/bin/cask /usr/local/bin/cask
+  cask
+  cask exec $EMACS -batch -l dev/ert.el -l dev/examples-to-tests.el -l dev/undercover-init.el -l s.el -l dev/examples.el -f ert-run-tests-batch-and-exit
+else
+  exec ./run-tests.sh
+fi