Updating go vet location in install-dev-tools target, as it has moved.

[robdaemon]

Fixes this error:

can't load package: the code.google.com/p/go.tools/cmd/vet command has
moved; use golang.org/x/tools/cmd/vet instead.

[cfdreddbot]

Hey robdaemon!

Thanks for submitting this pull request!

All pull request authors must have a Contributor License Agreement (CLA) on-file with us. Please sign the appropriate CLA (individual or corporate).

When sending signed CLA please provide your github username in case of individual CLA or the list of github usernames that can make pull requests on behalf of your organization.

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. You can view the current status of your issue at: https://www.pivotaltracker.com/story/show/85570392.

[robdaemon]

Corporate CLA for HP is already signed and on file, I'll get my individual one signed and emailed in tonight.

[simonleung8]

Thanks for the PR, merged.

[robdaemon]

@simonleung8 - this looks like it was closed without merging the change?

[simonleung8]

You are right, my mistake, it is really merged this time.
thanks for the look out.

[robdaemon]

I've done that more than once. Thanks!