add coveralls support

* and coverage badge to README

.travis.yml

@@ -3,3 +3,9 @@ perl:
   - "5.18"
   - "5.16"
   - "5.8"
+
+before_install:
+  - cpanm -n Devel::Cover::Report::Coveralls
+
+after_script:
+  - cover -test -report coveralls

README.md

@@ -1,6 +1,5 @@
-
-![Build Status](https://travis-ci.org/smtpd/qpsmtpd.svg?branch=master "Build
-Status")
+[![Build Status][ci-img]][ci-url]
+[![Coverage Status][cov-img]][cov-url]
 
 # Qpsmtpd - qmail perl simple mail transfer protocol daemon
 
@@ -177,3 +176,9 @@ If the logfile doesn't give away the problem, then post to the
 mailinglist (subscription instructions above).  If possible, put
 the logfile on a webserver and include a reference to it in the mail.
 
+
+[cov-img]: https://coveralls.io/repos/smtpd/qpsmtpd/badge.svg
+[cov-url]: https://coveralls.io/r/smtpd/qpsmtpd
+[ci-img]: https://travis-ci.org/smtpd/qpsmtpd.svg?branch=master
+[ci-url]: https://travis-ci.org/smtpd/qpsmtpd
+