Tizen extensions modifications

As per https://crosswalk-project.org/jira/browse/XWALK-1363
Manually install web application on Tizen IVI

A comment on XWALK-1363

https://crosswalk-project.org/jira/browse/XWALK-1363?focusedCommentId=17476

explains that it is not OK to use hard-coded user IDs to install
rpms on Tizen.

For that reason, use a manual install with xwalkctl to install
the web app part of the Tizen IVI extension example.
Fix poor formatting on Tizen target setup page
Remove duplicated 'run on Tizen' instructions
Merge pull request #106 from crosswalk-project/tizen-1363

Don't use an rpm for the web app in Tizen IVI extensions tutorial