Refactor findCommonUlPrefix to be generic enough to work with any url scheme, not just file://
Support passing in arguments or an array of urls
Added tests for findCommonUlPrefix
Handled cases with no common prefix on absolute urls with file and web-like protocols
Merge pull request #1 from assetgraph/commonPrefix

Refactor findCommonUlPrefix to be generic enough to work with any url scheme, not just file://