Add multiple source file and templating support to file.append (#6905)

Allow states/file.append() to use multiple source files and templating
to generate the text to be appended to the 'named' file.
Update Docstring
Assume a runlevel of 2 for Debian services if runlevel returns 'unknown'. Certain Linux Container environments do not run init, but the service module can still function properly.
Remove the warning about bug #7290 now its fixed.
Merge pull request #7335 from terminalmage/docs

Fix cmd.wait example
Merge pull request #7322 from echtish/debian-service-runlevel-unknown-fix

Assume a runlevel of 2 for Debian services if runlevel returns 'unknown'...
update release notes
Add encoding and docstring to grains package
Add encoding to modules package
add encoding and docstring for renderers
Add encoding and docstring for returners
Add encoding and docstring to runners dir
Add encoding and docstring to states dir
Add encoding and docstring for tops directory
Revert "Update file.py"

This reverts commit 76530a526edf418ea62bdda776edf517254670b4.
Update manpages with correct version number
Set version to 0.17.0
Added template context on rendering error

When a template rendering error occurs, show the part of the template
where the problem happened in order to make it easier to track down.
Added tests for error template context.
`0.17.0` has been tagged. The `0.16.x` `requires_network` is no longer necessary.