nfs exports: make async default

Sync in exports causes abysmal performance. We had this problem
in linaro lab, and also on my fresh install.

Since the data lava exports over nfs is ephemeral, async is a safe
option.

Change-Id: I1b2c93de43e2c17bbc3be1502b470df03b33130e
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
LAVA-1539 - Support for parameters in git-repos section of yaml

 * LAVA-1616 - Parameters within git-repos section of YAML
 * LAVA-1617 - Control parameters within git-repos section from job definition

Change-Id: Ic5e9ebab6df23702973c1e1fa27d7afc14990179
LAVA-1538: Add the ability to process params within the install section

 * LAVA-1618 Expose few parameters from JSON to YAML

Change-Id: I521001b34b19d84009f84983f767ae21be0ed92c
Remove FIXME that indicates usage of ast.literal_eval which was fixed.

Change-Id: I9014aabf821cc874b9c3266d723a106265eb8d59
Refresh the overlay class

LAVA-1586 - Use idempotent MultiNode and LMP actions
Create a separate overlay tarball and retain as part
of the final job.

Change-Id: I9bfcb3b1cb8ee98a94ae6c3946f07b1caf49dec8
Add support for Beaglebone-black

LAVA-1401, LAVA-1631 - initial device type configuration
files, tftp Deployment and u-boot Boot classes with unit
tests and sample job YAML.
LAVA-1670 substitute configuration details and filenames
into the commands.
LAVA-1701 - overlays for u-boot deployments
LAVA-1665 - Drop use of LavaDispatcherTestCase, use unittest.TestCase.

Change-Id: Ia84aaaf8e39aa84fcc3a4a293ac2e9e91f087637
Move download functions into actions.

Only http/https/file schemes are supported for the moment.
The progress bar is not shown for the moment but can easily be added later.

Change-Id: I0d7be50b5fa54be51ead50bfb13e9abe3cd37bae
Allow for empty run_command output

Change-Id: Ib2876b27a7ec1d08dc925c8c71db7936d7505da5
Initial JSON repeat action.

Change-Id: I0b7b9eb1483c202f50fe88bc82f92f299bc18be2
Fix PEP8 introduced in 95dd980

Change-Id: I68ec1fb8a4aab1bbd37e592cae5b880550bff05d