Make certain that path is relative before joining it to relativeTo
Added tests for windows based pathname resolution
Stole absolute path check from gruntjs since Path.normalize wasn't reliable

Also updated the schema validation for relativeTo on the server to allow
for Windows based paths
Made a utility method for isAbsolutePath. Better checking
Added tests for checking isAbsolutePath
Test isAbsolutePath with empty path
Regex handles all path starting options (including Azure paths)
Formatting
Formatting
Tests for invalid paths in isAbsolutePath
Merge pull request #1547 from andrewburgess/issue-1545

Make certain that path is relative before joining it to relativeTo