If a Tool entry has been changed on a server to point to a different

SCMTool class, we'll crash with an IntegrityError when trying to

inject tools, due to a conflict in names.
We now check for both name and class_name conflicts. If we try to

record a SCMTool as a Tool, and either the name or class (but not

both) matches an existing Tool, we'll log a warning and record the

conflicting tool.
The upgrade handler looks to see if we detected any conflicting tools,

and if so, provides warnings and guidance on the conflict.
This will hopefully help for companies that have forked some SCMTool

for their own needs.

Hit this issue when temporarily modifying a class name for a tool to

trigger an entirely different error, and saw the crash during upgrade.
Verified that this no longer crashes, but rather displays a block of

information with the details on the conflict.
Unit tests pass.