Clang kitchen sink

This is a relatively large PR with more than a single feature.
summary:
- fixes to get Grappalang code to run well on large cluster
- fixes to run sp2bench
- logging and timing
- symmetric hash join, fully pipelined
- insertion queries (no syntax yet)
- clang tests. These are in `c_test_environment/clang_tests.py` and have `@nottest` set because they break in the travis.ci environment. They can be run outside of nose tests with `python clang_tests.py`.

notes:
- no changes to shared infrastructure outside of clang