update API calls to Solve to match 1.0.0.dev
add dependencies instead of read dependencies in graph
blank strings or empty arrays aren't valid constraints
remove resolver features

these are no longer needed since we're using the gecode resolver in Solve
add libgecode to travis install packages
Merge pull request #1104 from berkshelf/update-solve

Update API calls to Solve to match 1.0.0.dev