Run BFGMiner's unit tests for 'make check', and have --unittest exit with failure if any problems occur
Travis build configuration
Travis: No need to upgrade GCC for LLVM build
Travis: Upgrading GCC triggers locale rebuild, so just do the one in use
Travis: Build with libsensors and VFIO
Travis: Test many configuration variations
Travis: Perform full builds with libbase58's base58 tool (which is used for tests)
Merge branch 'travis' into bfgminer