Satis configuration file description

Better upfront description of what a Satis configuration file actually is. Was previously not clear the name didn't matter until further down.
Further simplified Satis Config intro
optimizing loops
removing incorrect optimization
Merge pull request #1615 from shanethehat/loop-optimization

Optimizing loops
Specific schema validation failure messages (fixes issue #1616)
Add other valid versions to test for stability
adding use statement
Merge pull request #1618 from ChristianRiesen/master

Small enhancement of test to test more stable version strings
Merge pull request #1617 from shanethehat/schema-validation-messages

Specific schema validation failure messages (fixes issue #1616)
Merge pull request #1609 from jeffturcotte/patch-1

Satis configuration file description