Updates kernel config tests for /boot perms
Updates kernel config tests for /boot perms

As of the upgrade to 4.14.175 kernels, the entire /boot directly is 700
root:root. That means we'll have to use sudo on the testinfra checks
reading files in there, particularly the kernel config.

conorsch/securedrop,conorsch/securedrop,conorsch/securedrop,conorsch/securedrop,conorsch/securedrop