Bootstrap-salt RHEL Updates

Added:
- Check to see if EPEL is installed before it tries to install
- Added wait loop to before optional packages are installed.  This is
to wait for RHEL to finish registering
- Updated -eq 6 && -gt 6 to just -ge 6
Updated wait state

searches for python-jinja2 instead for the optional repos.
Fix `OR` syntax error
Properly identify Amazon Linux AMI using `lsb_release`. Fixes #416.
Update changes log
Ignore SC2035
Bump version.
Only require PIP based installations for Debian < 7. Fixes #424.
Replace `packages` for `__PACKAGES` to "hide" the variable name
Update changes log
Install `python-zypp` on SuSE and openSUSE

This is required by Salt's `zypper` module.
Update changes log
Explicitly disallow installation attempts for Amazon Linux AMI 2010.xx

Fixes #426
Update changes log
Make shell check happier
CentOS 7 now uses SystemD instead of SysV

Ensure centos 7 is capable of using systemd for checking if the service is running/restarting
Only install EPEL if not already installed.

Refs #422. Closes #421.

Enable the systemd service. Closes #425.
Update changes log
If system is using systemd, enable services.

Closes #425.
Install `salt-api` scripts if `salt-master` is installed.

Fixes #415