Stop ignoring 400 errors returned by ODL

This commit stops ignoring 400 (Bad Request) HTTP codes returned by ODL
in create and update operations. It also modifies sendjson() because it
doesn't ignore any HTTP error code now.

Change-Id: Id0db2c0c1d8fddfbd16b3ce9476a2358e2ef1e49
Closes-Bug: #1369239
Merge "Stop ignoring 400 errors returned by ODL"