add --tags to 'git describe'

'git describe' calculates the version since the last **annotated** diff. Adding --tags shows the most recent tags (v0.94, for example) regardless if they're annotated or not.
put git version detection code into a sub
remove test counters from plugin tests

replace with done_testing(), which provides the same "make sure to kvetch if tests fail to run" without requiring humans to do the bookkeeping.
Merge pull request #107 from msimerson/version

add --tags to 'git describe'
Merge pull request #110 from msimerson/tests

remove test counters from plugin tests
async removed

1. the known users of async don't upgrade
2. async becomes a win when concurrent connections exceed a few hundred simultaneous
3. anyone that needs async should be looking at Haraka instead
4. the perl async dependencies aren't maintained
Merge pull request #114 from msimerson/async

async removed
updated MANIFEST
Merge pull request #115 from msimerson/async

updated MANIFEST
qpsmtpd.t: added tests for hook_responder
Qpsmtpd: style changes in hook_responder
added test for run_continuation
added tests for run_hooks & run_hooks_no_respond
simplify config->from_file by not requiring full

file path. Instead, figure it out the same way as the 4 of the 5 caller do (by calling config_dir). Allow the 2nd arg to be the file name.
remove YIELD cruft introduced by rebase
Merge pull request #112 from msimerson/qpsmtpd.t

Qpsmtpd.t
Remove a ton of 'return ()', and a few other minor readability tweaks.
Silence a noisy test by passing an expected data type.
Merge pull request #120 from smtpd/test_warning

Silence a noisy test by passing an expected data type.
Merge pull request #119 from flimzy/return_cleanups

Remove a ton of 'return ()', and a few other minor readability tweaks.