feat(omaha): add bootid and machineid

This returns the oem="" and machineid="" field in the app parameters
using the /etc/oem-release file and the /etc/machine-id file
test(*): make all the tests pass

Cleanup all of tests so they pass. It has been months since these tests
have all passed.
fix(omaha_request_action_unittest): always including a machineid

On CoreOS we always include the machineid if available. Delete this
test.