possible fix for https://github.com/saltstack/salt/issues/5567
possible fix for https://github.com/saltstack/salt/issues/5567
Add salt.utils.master with class MasterPillarUtil. Change salt.runners.cache to use salt.utils.master.MasterPillarUtil
Remove unnecessary variables.

Somewhere along the way salt's setup changed and some variable were left around. Let's remove them.
Make pylint happy, global variables are all uppercased.
Allow salt's paths to be configurable at build time.
Double to single quotes.
Minor formatting updates.
No more hard-coded salt paths.

All system paths that salt expects and needs are all configurable at install time. This allows for packagers to setup salt's **default** internal paths at build time. For example, under windows, the configuration directory is expected at `c:\salt\conf\`, on FreeBSD at `/usr/local/etc/salt`, etc.

The configurable paths are:

* Salt root directory, `salt_root` in the master and minion configuration files, `--salt-root-dir` option to `python setup.py install`.  Default: `/`
* Salt configuration directory, `--salt-config-dir` option to `python setup.py install`.  Default: `/etc/salt`
* Salt cache directory, `--salt-cache-dir` option to `python setup.py install`.  Default: `/var/cache/salt`
* Salt sock directory, `--salt-sock-dir` option to `python setup.py install`.  Default: `/var/run/salt`
* Salt services root directory, `--salt-srv-root-dir` option to `python setup.py install`.  Default: `/srv`
* Salt base file roots directory, `--salt-base-file-roots-dir` option to `python setup.py install`.  Default: `/srv/salt`
* Salt base pillar roots directory, `--salt-base-pillar-roots-dir` option to `python setup.py install`.  Default: `/srv/pillar`
* Salt base master roots directory, `--salt-base-master-roots-dir` option to `python setup.py install`.  Default: `/srv/salt-master`
* Salt logs directory, `--salt-logs-dir` option to `python setup.py install`.  Default: `/var/log/salt`
* Salt pidfile directory, `--salt-pidfile-dir` option to `python setup.py install`.  Default: `/var/run`
Adapted `unit.modules.virtualenv` to use `salttesting.mock`
Adapted `unit.modules.alternatives_test` to use `salttesting.mock`
Adapted `unit.modules.win_status_test` to use `salttesting.mock`
Adapted `unit.modules.archive_test` to use `salttesting.mock`
Adapted `unit.modules.gem_test` to use `salttesting.mock`
Adapted `unit.modules.pip_test` to use `salttesting.mock`
Adapted `unit.modules.poptgres_test` to use `salttesting.mock`
Adapted `unit.modules.rvm_test` to use `salttesting.mock`
Adapted `unit.payload_test` to use `salttesting.mock`
Adapted `unit.pillar_test` to use `salttesting.mock`
Adapted `unit.utils.warnings_test` to use `salttesting.mock`