Separate lock reason from summary

We recently adjusted to display the moderation reason of a topic directly
in the topic titlebar.  Since locking/unlocking a topic was setting both the
moderation reason and the summary duplicate content is being displayed. We
decided to split the two, showing the lock reason and leaving the summary alone
for usage as the users see fit.

This patch changes the locking forms and apis to accept the reason argument
instead of summary, and removes the code in the TopicSummary block that responds
to the lock-topic action.

Change-Id: Ic576481b1215f1ab0bd836915900a34a48f7047b
(cherry picked from commit e93057a458b9691f6a9710b5ad92f63db5259805)
Merge "Separate lock reason from summary" into wmf/1.25wmf2