Check keypair destroy result operation

This checks the result of delete operation over keypairs to see if it
affected any row (this is what delete returns), if not raises
KeyPairNotFoundException.

Also adds tests for keypair db api.

Fix bug 1086980

Change-Id: I7e822c0661c563db01040ae2d57aacfe677d72b0
Merge "Check keypair destroy result operation"
Merge remote-tracking branch 'm_src_repo/master' into build-temp