Add <source> path and make class filenames relative to the source path

This fixes gotwarlost/istanbul#50 by giving source paths where Jenkins
can find the source files in order to archive them and paint the source
with proper coverage styles.
Set initial cover count for function declarations as 1 and never increment, fixes #67
Update changelog, up version
Address windows path separator issue
Merge pull request #51 from MeetMe/cobertura-source-paths

Add <source> path and make class filenames relative to the source path