Store lint output in the build tree

[jack-oquin]

Creating an output file would be useful for users.

Such a target should cause the lint command only to run again when its dependencies change.

[mikepurvis]

As discussed in #11, the ideal would be if there could be output generated in xUnit format, so that failures in the buildfarm can provide intelligent feedback without you having to go through the stdout log. Some info on creating simple test reports for Jenkins.