These were found by a combination of manual review and a custom script
that checks for common errors.

Also removed an outdated sentence from the comment for setupBefore().

Per the FHS, manually installed programs should go under /usr/local.
This change also makes it easier to change the global installation
prefix. For example, package managers should set PREFIX=/usr

Running "go vet -shadow ./..." finds all places where a variable might
be incorrectly or unnecessarily shadowed. This fixes some of them.

Our current build tags set off the linter. We will later add in more
comprehensive build tags that will be properly formatted.

Now the offending panic will just be logged and the module will fail.
This is important as to not crash the login process.