Fixed problem for transaction test mode.

trans_complete function is committed in test mode.
Because any database drivers are set _trans_failure in test_mode,
And trans_complete function is not evaluate _trans_failure.
fixed for styleguide.

|| to OR
remove the empty line at EOF
Fixed for styleguide.
Add common robot user agents.
Merge pull request #2382 from garthkerr/add-bot-agents

Add common robot user agents.
Merge pull request #2343 from QOX/develop

Fixed problem for transaction test mode.
Add a changelog entry for PR #2343
Fix #2380 and deprecate CI_Router::fetch_*() methods