Update API comparison using frappuccino.

We sleep one second to make sure the bytecode cache is not loaded,
And we give extra seeds modules to crawl the API

tools/release_helper.sh

@@ -108,12 +108,14 b' if ask_section "Generate API difference (using frapuccino)"'
 then
     echo $BLUE"Checking out $PREV_RELEASE"$NOR
     git checkout $PREV_RELEASE
+    sleep 1
     echo $BLUE"Saving API to file $PREV_RELEASE"$NOR
-    frappuccino IPython --save IPython-$PREV_RELEASE.json
+    frappuccino IPython IPython.kernel IPython.lib IPython.qt IPython.lib.kernel IPython.html IPython.frontend IPython.external --save IPython-$PREV_RELEASE.json
     echo $BLUE"comming back to $BRANCH"$NOR
     git checkout $BRANCH
+    sleep 1
     echo $BLUE"comparing ..."$NOR
-    frappuccino IPython --compare IPython-$PREV_RELEASE.json
+    frappuccino IPython IPython.kernel IPython.lib --compare IPython-$PREV_RELEASE.json
     echo $GREEN"Use the above guideline to write an API changelog ..."$NOR
     echo $GREEN"Press any keys to continue"$NOR
     read