Only install EPEL if not already installed.

Refs #422. Closes #421.

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

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

Fixes #415
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Allow a little more time to cancel
Configurable sleep value. Fixes #413

Support a configurable sleep time when starting, restart and checking
for enabled service.
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`oracle-release` should come before `redhat-release`. Fixes #409.
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Remove more than a single white-space
Merge pull request #429 from s0undt3ch/develop

Fixes and Improvements