Base for new dispatcher design

Merge in pipeline support
Add YAML line number retrieval.
Merge CompositeAction into Pipeline

Change-Id: I75cfec232c83340adb77d3ca85cce32da2086846
Fix very basic python3 issues

These are for loading setup.py under python3, but the tests fail right
away because of some other misterious issues which still need to be
investigated.

Change-Id: I3cbef567b10dc0fe8bd1e123fb5ea7614dc02452
Provide debranded version of command names

Command names that contain "linaro" in it can now also be referenced by
the same name but without "linaro". The preexisting linaro-branded names
can still be used.

- deploy_linaro_image -> deploy_image
- boot_linaro_image -> boot_image

Change-Id: Icfb197f7c811c9674e57866691c5e612bbe20aef
Use LAVA_PROXY for git and bzr clone

This commit complete the work done in 33bc1c711bf4bd1004891cbeeff79b0f8ad64a5a

Change-Id: Ifec28b55154150dcf1f74fe0b1973a160e7bf86b
Factorize http_proxy settings

Change-Id: Ie44f13eb092f91f4d51fcbbffded591722ec0a09
fastmodels: run models as lavaserver user, and adjust permissions for temp directory

* lava-dispatcher package already depends on sudo
* packaging installations using lava-server 
  create a 'lavaserver' user by default

Change-Id: I3dfee93966faca824a98efad81f229394429665a