predeactivate and postactivate hooks

--HG--
extra : convert_revision : svn%3A98f53aa3-d424-0410-b225-a548b0275c4d/Projects/virtualenvwrapper/trunk%401355

Author: dhellmann

virtualenvwrapper_bashrc

@@ -87,10 +87,14 @@ function workon () {
         echo "ERROR: No activate for $WORKON_HOME/$env_name"
         return 1
     fi
+    if [ -f "$VIRTUAL_ENV/bin/predeactivate" ]
+    then
+        source "$VIRTUAL_ENV/bin/predeactivate"
+    fi
     source "$activate"
-    if [ -f "$WORKON_HOME/$env_name/bin/workdir" ]
+    if [ -f "$VIRTUAL_ENV/bin/postactivate" ]
     then
-        source "$WORKON_HOME/$env_name/bin/workdir"
+        source "$VIRTUAL_ENV/bin/postactivate"
     fi
 	return 0
 }