Added a failing test for #190
Always consider left and right nodes when sorting

If we have bad luck (as in #190), all our dependent nodes might get
passed in on the left-hand side, and would therefore not consider their
dependencies under the old algorithm.
Use more verbose names, stick with lhs/rhs
Compare project names if dependency count is equal
Merge pull request #191 from Carthage/fix-cartfile-lock-ordering

Fix nondeterministic Cartfile.lock ordering