packaging: use wildcard for test files in Debian

This pull request updates the Debian packaging to use test_* instead of listing all test_xx files individually.

Thanks very much to @hjwsm1989 for reporting the issue and initial patch to ceph-devel.

A test build is [available in gitbuilder](http://gitbuilder.sepia.ceph.com/gitbuilder-ceph-deb-precise-amd64-basic/log.cgi?log=364fed816aa5dfa3ba12b43061350fc442e08243). `dpkg -c ceph-test_0.77-630-g364fed8-1precise_amd64.deb` shows that the test files are present in the deb.

With this commit, ceph-test now includes the following three files that were absent in ceph-test from master (225eb4a7be1af95688121c0e295b234a236a1b52):

* `/usr/bin/ceph_test_c_headers`
* `/usr/bin/ceph_test_get_blkdev_size`
* `/usr/bin/ceph_test_rgw_manifest`