Fix BL-827: Hard to insert uppercase special character

This fix makes the popup stay visible as long as you're holding down the shift key.
Fix BL-843 "Update Book" corrupts custom pages

Update Book was written before we had custom pages, so it blindly tries to make pages conform to their ancestor in the BasicBook template. This commit excludes pages with the "customPage" class from that process.
Allow multiple test runs at the same time

Now that we have the tests running on both Windows and Linux some
of the tests randomly fail. It looks like it's caused by a race
condition when the same test runs multiple times at the same time.
This change improves several of the tests that interact with
Amazon S3 by adding a random part to the username and directory
name.
Merge pull request #206 from BloomBooks/BL843UpdateBookWipesOutCustomPages

Fix BL-843 "Update Book" corrupts custom pages
Merge pull request #204 from BloomBooks/BL827LongPressWithShiftAndUppercase

Fix BL-827: Hard to insert uppercase special character
Merge pull request #208 from ermshiperete/FixFailingTests

Allow multiple test runs at the same time