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`