Switch from requests library back to urllib2

Not worth it due to difficulty getting requests to work on app engine
at this time. Leave put_blob on requests because there's no trivial
multipart upload with urllib2.

Mostly reverts commit 4454ac829cbd8b0719ef542b93ba9aa433660f35.
Revert "Update baqup and wordpress examples for new get_blob behavior"

Since we're back to urllib2

This reverts commit 7e0db5d6482008f6e7441d69259d052d1716992f.