Make init script creation optional

Packages often install init scripts.  This makes the writing of an init script
optional, allowing pallet's initd service abstraction to be used with package
provided init scripts.
Add group-node-maps to return node maps

Returns a sequence of node maps for the specified group specs.
Fix ensure-service-dispatch in hybrid provider
Add spool-root to p.script.lib

Returns the root directory for spool files, usually /var/spool.
Log ssh port when executing remote scripts
Allow tmpdir specification in make-temp-file
Allow action specific script context

The :script-context action option can be used to specify a sequence of additional
script context keywords for an action.
Allow control of hashing in scripts

The :script-hash option can be used to control whether the shell hashes executable
paths.  Defaults to true.
Ensure ssh-mktemp respects TMPDIR in :script-env
add missing :all-node-set in 'lift-options-schema'.
Fix os-family in package-test
Update to stevedore 0.8.0-beta.4
Add :extract-files option to 'remote-directory

Allows the specification of which files or directories to extract from a
jar, zip or tar archive.
fix some typos