variable
Previously, there were two ways to configure Vmpooler, either by
changing the contents of vmpooler.yaml or by assigning the raw YAML
to the VMPOOLER_CONFIG environment variable. This commit adds a new
environment variable called VMPOOLER_CONFIG_FILE that can be assigned
the name of a config file to use. Also fixes#240 by whitelisting the
Symbol class when calling YAML.safe_load in Vmpooler.config.
This commit adds documentation for how to setup a development environment for
VM Pooler. This commit also moves the API under the new docs directory and
modifies the README appropriately.