Fix env variable name.
Remove unused import.
Remove -f flag from test cases.
Move target flag to the end such that it doesn't consume the filename.
Merge pull request #29 from runefriborg/develop

Fixed issue where the first target was ignored, if @target was the first...
Fixed issue where the first target was ignored, if @target was the first line in the .gwf file.
Always run commands in sandbox directory.
Fix test with large fan-out.
Fix workflow graph test.
Use None as default value, since we change it anyway.
Merge branch 'feature/integration-tests' into develop
Merge branch 'develop' of github.com:dansondergaard/gwf into develop