[autotest] Eureka host.

Creates a eureka host capable of verifying, cleanup, reboot
and machine_install. Also implements the following chagnes:
1. Pipes a base command through is_up, since different ssh
   hosts are bound to have different things pre-installed.
2. Changes some timeouts to integers to avoid asserts.
3. Make host factory a little more generic, and check
   for chromeos host first.
4. Adds a method to remote wget to server/site_utils.

TEST=Tried verify, cleanup, reoboot and machine_install.
BUG=chromium:292629, chromium:273843

Change-Id: I62a700614838569c6d77184b3c3339e914f4b456
Reviewed-on: https://chromium-review.googlesource.com/176303
Tested-by: Prashanth B <beeps@chromium.org>
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
Commit-Queue: Prashanth B <beeps@chromium.org>
10 files changed