Release 4.4.0

Summary
This release has an overhauled readme, new private manifest function,
and fixes many future parser bugs.

Features
- All new shiny README
- New `private()` function for making private manifests (yay!)

Bugfixes
- Code reuse in `bool2num()` and `zip()`
- Fix many functions to handle `generate()` no longer returning a string on new puppets
- `concat()` no longer modifies the first argument (whoops)
- strict variable support for `getvar()`, `member()`, `values_at`, and `has_interface_with()`
- `to_bytes()` handles PB and EB now
- Fix `tempfile` ruby requirement for `validate_augeas()` and `validate_cmd()`
- Fix `validate_cmd()` for windows
- Correct `validate_string()` docs to reflect non-handling of `undef`
- Fix `file_line` matching on older rubies