Clear environment before config loader tests

Fixes #319
fix issue 326 ("flags --column and --context together produce an error") with test
Merge pull request #396 from bartlomiejb/dev

Fix issue #326 ("flags --column and --context together produce an error")
Don't hardcode separator comparison for column print check
Merge pull request #392 from dagolden/topic/fix-config-loader-test

Clear environment before config loader tests
Added Stephan Hohe to acknowledgements
Added test for testing highlighting
Add missing use of Term::ANSIColor to Util.pm
Test -g + --color
Implement -g + --color
Document -g + --color
Add test for illegal --output in project ackrc
Change protocol for passing arg sources around
Change ConfigFinder to return structures of data
Expect config finder to set project = 1 for project files
Flag project files in config finder
Thread project flag through config loader
Fix up illegal --output test
Make certain options illegal in project ackrcs

Namely --output, --pager, --match
Fix typo