webkit-perf.appspot.com should have an ability to merge tests

webkit-perf.appspot.com should have an ability to merge tests
https://bugs.webkit.org/show_bug.cgi?id=77250

Reviewed by Adam Barth.

Added admin/merge-tests. This page allows administrators to easily merge test objects.

Also add the forgotten title.png and rename api/create to admin/create since we don't allow
non-admins to create new models anyway.

* Websites/webkit-perf.appspot.com/app.yaml:
* Websites/webkit-perf.appspot.com/css: Added.
* Websites/webkit-perf.appspot.com/css/title.png: Added.
* Websites/webkit-perf.appspot.com/main.py:
* Websites/webkit-perf.appspot.com/merge_tests.yaml: Added.
* Websites/webkit-perf.appspot.com/merge_tests_handler.py: Added.
(MergeTestHandler):
(MergeTestHandler.get):
(MergeTestHandler.post):
* Websites/webkit-perf.appspot.com/models.py:
(deleteModelWithNumericIdHolder):
* Websites/webkit-perf.appspot.com/static/create-models.html:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@106292 268f45cc-cd09-0410-ab3c-d52691b4dbfc