[NaCl SDK] AppEngine: URL paths /demo/<example name> works.

* /demo works now
* Also moved /static/pnacl-demo-<foo> => /static/foo
* Redirect /demo/<garbage> to /demo/
* Stripping final slash: /demo/bullet/ => /demo/bullet
* Clicking a link will correctly update your URL

BUG=none
R=sbc@chromium.org

Review URL: https://codereview.chromium.org/67473003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234057 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234057
Implement chrome.identity.generateRedirectURL

BUG=132674

Review URL: https://codereview.chromium.org/32223002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234058 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234058