Travis binary packages

This ready-to-merge branch makes the travis testing use binary packages from conda instead of building dependencies from source, thereby decreasing test time significantly (testing is still slow but now it is slow because the testing takes a long time not because of setting everything up). The problem mentioned in #148 had to do with Anaconda shipping its own `math.h` file, weave needs to set the `include_dirs` option to work with it (this is now a new preference).

Closes #148.