Added base graph files, and excluded in gitignore.
Updated base graph files for Linux and make test only run on Linux.
Added test to compare DOT files (Jure's suggestion.
Added test to compare DOT files (Jure's suggestion).
Merge branch 'master' of github.com:nshelly/snap
Merge branch 'master' of git://github.com/snap-stanford/snap
Merge branch 'master' of git://github.com/snap-stanford/snap
Merge pull request #9 from nshelly/master

Updated GraphViz for Linux and Mac graph tests.