undelete overzealously removed plugin initialisation (#61)

* undelete overzealously removed plugin initialisation
* tersify pkg_resources/directory calls since we don't care about errors

morituri/rip/main.py

@@ -17,6 +17,11 @@ def main():
     # set user agent
     musicbrainzngs.set_useragent("morituri", configure.version,
         'https://thomas.apestaart.org/morituri/trac')
+    # register plugins with pkg_resources
+    distributions, _ = pkg_resources.working_set.find_plugins(
+        pkg_resources.Environment([directory.Directory().getData('plugins')])
+    )
+    map(pkg_resources.working_set.add, distributions)
     c = Rip()
     try:
         ret = c.parse(sys.argv[1:])