book update: map -> mappedBy; html event handling and httprequest changes

The main changes are here:
http://book.dart-lang.appspot.com/docs/dart-up-and-running/contents/ch03.html#ch03-httprequest

Also see the summary of updates, so far:
http://book.dart-lang.appspot.com/docs/dart-up-and-running/contents/preface.html#preface-updates

Ignore the changes to contents/index.html. That file is mostly hidden, and the changes appear to be spurious (maybe due to a remote stylesheet adding links where none used to be before).

Review URL: https://chromiumcodereview.appspot.com/12226066
Updated code to work with r18115
Merge pull request #35 from chrisbu/json_object_18115

Updated json_web_services article code to work with r18115
Minor changes: figure note, innerHTML -> innerHtml

Review URL: https://chromiumcodereview.appspot.com/12209121
update online copy of book

Review URL: https://chromiumcodereview.appspot.com/12250007
fix episodes

BUG=

Review URL: https://chromiumcodereview.appspot.com//12218121
add lang-* remarks to enable pretty print

See https://github.com/dart-lang/dart-up-and-running-book/issues/21

Review URL: https://chromiumcodereview.appspot.com/12220127
Unit test article fixes

BUG=

Review URL: https://chromiumcodereview.appspot.com/12221149
add new presentation

staged at http://jfokus-preso.dart-lang.appspot.com/

Review URL: https://chromiumcodereview.appspot.com//12223105
Add Snapshots article and an author page for Siva.

Staged at:
http://snapshots.dart-lang.appspot.com/articles/snapshots/
http://snapshots.dart-lang.appspot.com/authors/siva-annamalai.html

Review URL: https://chromiumcodereview.appspot.com/12258014
lose the "much, much"

BUG=

Review URL: https://chromiumcodereview.appspot.com/12259014
A first draft on the article on using futures based APIs

BUG=

Review URL: https://chromiumcodereview.appspot.com/12207136
minor copyedits to Future article

TBR=shailentuli

Review URL: https://chromiumcodereview.appspot.com/12254027
handle optional training slashes

The patch you've been waiting for!

staged at: http://optional-trailing-slashes.dart-lang.appspot.com/

Review URL: https://chromiumcodereview.appspot.com//12212176
reapply patch

BUG=

Review URL: https://chromiumcodereview.appspot.com//12261044
add warning about importing multiple configs

A reader reported some confusion about this.

To see the change in context, go to http://fixes.dart-lang.appspot.com/articles/dart-unit-tests/#basic-synchronous-tests and scroll up a windowful.

Review URL: https://chromiumcodereview.appspot.com/12253042
first section of httprequest, GET, URIs

BUG=

Review URL: https://chromiumcodereview.appspot.com/12093113
tweaks from kathy

BUG=

Review URL: https://chromiumcodereview.appspot.com//12280011
update the IO codelab

BUG=

Review URL: https://chromiumcodereview.appspot.com//12276011
fix codelab, using timer and duration