feat(makefile): enable make install for ubuntu

Fixes #

Helps #57

Description: Update Makefile for other OS

Add Makefile support for Ubuntu
Add indentation for "Other OS" so developers can read easier.
Ensure python3 is default python

Checklist:

[ no ] Added unittests and or functional tests
[ no ] Adapted documentation
[ yes ] Referenced issues or internal bugtracker
[ no ] Ran integration tests successfully (trigger with "@susebot run teuthology" in a GitHub comment; see the wiki for more information)

Note Adding support for other OS will require more PR. This Makefile was tested on Ubuntu 18.04.

root@ubuntu1804:/tmp/deepsea_tmp/DeepSea# make install
                  #make sure to create bytecode with the correct version
                  find srv/ -name '*.py' -exec python3 -m py_compile {} \;
                  find cli/ -name '*.py' -exec python3 -m py_compile {} \;
                  # Using '|| true' to suppress failure (packages already installed, etc)
                  rm /usr/bin/python && ln -s /usr/bin/python3 /usr/bin/python 2>/dev/null || true
                  apt-get install -y salt-api || true
                  Reading package lists...
                  Building dependency tree...
                  Reading state information...
                  salt-api is already the newest version (2019.2.0+ds-1).
                  The following packages were automatically installed and are no longer required:
                    python3-cherrypy3 python3-repoze.lru python3-routes python3-simplejson
                    python3-webob
                  Use 'sudo apt autoremove' to remove them.
                  0 upgraded, 0 newly installed, 0 to remove and 147 not upgraded.
                  apt-get install -y python3-setuptools python3-click tox python3-configobj || true
                  Reading package lists...
                  Building dependency tree...
                  Reading state information...
                  python3-click is already the newest version (6.7-3).
                  python3-configobj is already the newest version (5.0.6-2).
                  python3-setuptools is already the newest version (39.0.1-2).
                  tox is already the newest version (2.5.0-1).
<< CUT >>
                  removing '/usr/local/lib/python3.6/dist-packages/deepsea-0.0.0.egg-info' (and everything under it)
                  Copying deepsea.egg-info to /usr/local/lib/python3.6/dist-packages/deepsea-0.0.0.egg-info
                  running install_scripts
                  Installing deepsea script to /usr/local/bin

SUSE / DeepSea

feat(makefile): enable make install for ubuntu #1695