Remove preload tests until review is complete.

These tests are great, but they were written against Presto and
test a bunch of things that are not in the spec. This is being fixed
in r/604 but until then it seems better to remove them since some of the
problems lead to instability in results.
Use the correct name when deleting the database
Don't assume r-o transaction is blocked on r/w tx

The spec (currently) allows a r-o transaction created after a r/w transaction to snapshot the database rather than waiting until the r/w transaction has committed. The test is assuming that the transactions must be sequenced.

Don't start the second tx until the first has committed.
Correct expected exception type when open() fails

Per the spec [1]: "If the "versionchange" transaction in the previous step was aborted ... return a DOMError of type AbortError and abort these steps."

[1] https://dvcs.w3.org/hg/IndexedDB/raw-file/tip/Overview.html#opening
add tests for notification attributes method and event
update tests for notification description
Update tests for removing prefix in notification
Don't assume exception priority

Per resolution of bug 17681, for IDB "v1", which exception is thrown when two error cases apply is not strictly defined. *sigh*

https://www.w3.org/Bugs/Public/show_bug.cgi?id=17681
Use https URL for submodules to help with firewalls.
Merge pull request #845 from w3c/jgraham/remove_preload

Remove preload tests until review is complete.
cc Added some ins|del@datetime validator tests.
cc Restored some accidentally-deleted files.
cc Checkpointed messages.json file.
cc Minor housekeeping.
versionchange should be seen when deleting db
Merge pull request #848 from inexorabletash/master

Correct IndexedDB test issues
Add a test for missing a 'rel' attribute
Mention installing html5lib to run the tests in the README.md
fix testcommon.js path
Merge pull request #856 from SangsooNam/sub-imports-missing-rel

Add a test for missing a 'rel' attribute