tests: Bring utils.go test coverage back to 100%.
tests: Bring utils.go test coverage back to 100%.

#253 inadvertently removed an os.Chdir test in TestRuntimeConfig() that
was exercising resolvePath().

Add a new test in the correct place to handle this scenario.

Signed-off-by: James O. D. Hunt <348fbaadfbada55ea105602bf5609e23ac1c4898@intel.com>

clearcontainers/runtime,clearcontainers/runtime,devimc/runtime,devimc/runtime,chavafg/runtime,chavafg/runtime