Bazel support

[marczych]

I spent some time converting the project to use Bazel. I ran into some issues that I couldn't fix and decided it would give the project a higher barrier to entry so I ultimately decided to ditch it. I don't love Make but at least it's very well known and works just about everywhere. It's also easy to tweak the settings to work on any particular machine. I'm going to leave this pull open in case somebody wants to continue working on it.

The issues:

• Bazel isn't terribly mature so documentation is lacking and/or potentially out of date.
• The most confusing part of Bazel is the toolchain. I realized that I have no idea what determines which compiler is used on a given machine. I can create a CROSSTOOL but that's a huge amount of effort and probably won't be cross platform anyway.
• I couldn't get OpenMP to work which results in a huge performance hit.